Converted Jews fall into the house of Judah and converted Gentiles fall into the house of Israel. Paul actually uses this analogy in Romans 9 where he quotes from Hosea as they which were not a people shall be called the children of the living God. If we go back to Hosea the prophet was actually talking about the house of Israel or the ten northern tribes and Paul uses it as a reference to the Gentiles. The house of Israel was lost to history so God brought in the Gentiles to fill the ranks.
Your reading of Romans is completely off.
If you carefully break down its' sections for what it is that Paul is making use of as; he attempts to point some things out...
It becomes obvious that he is basically laying out for posterity - to his kinsmen according to the flesh: to fellow Israelites (as well as to Gentiles)...
Various examples from Israel's long history with God, wherein He had ALSO delayed His pending PHYSICAL wrath (for their disobedience) prior to His blessing them once more - where He had delayed both said pending wrath and blessing once more, that He might do one thing or another, FIRST....
Be it proving His Sovereignty; or bringing to pass, some other intent on His part, FIRST.
In this, Paul's "As He saith ALSO in Osee" is just one more example of those times in Israel's long history as to that, that Paul is basically reminding Israel of.
Read Hosea - His pending PHYSICAL wrath followed by His blessing - BOTH of which He ALSO saith unto them back then; He was delaying (back then); that He might do something else FIRST - which was what He did - back then as well.
EVERY SINGLE EXAMPLE Paul cites in Romans 9 points this out, in answer to the Israelite question Paul is dealing with...
Romans 9:18 Therefore hath he mercy on whom he will have mercy, and whom he will he hardeneth. 9:19 Thou wilt say then unto me, Why doth he yet find fault? For who hath resisted his will?
The Israelite depicted in Unbelief at the beginning of Romans 3, asks in Romans 9 - "Okay, so He is Sovereign - so what's the hold up now?"
He wants his unmerited cake, and he wants to eat it to.
Thus, the arrogance of many of them, even now; even on this forum, as to all this.
In this, Romans 9:26 is a confirmation, not so much of verse 25, but of assertions in verses 24 and prior, and so on.
Of God's right to change course, delay His plan and Purpose as to Israel for a time; do something else He had intended on doing, and after that, turn back to deal with His plan and purpose as to Israel...at last.
Notice...
Romans 9:27 Esaias also crieth concerning Israel, Though the number of the children of Israel be as the sand of the sea, a remnant shall be saved: 9:28 For he will finish the work, and cut it short in righteousness: because a short work will the Lord make upon the earth. 9:29 And as Esaias said before, Except the Lord of Sabaoth had left us a seed, we had been as Sodoma, and been made like unto Gomorrha.
Notice now...
Romans 9:30 What shall we say then? That the Gentiles, which followed not after righteousness, have attained to righteousness, even the righteousness which is of faith. 9:31 But Israel, which followed after the law of righteousness, hath not attained to the law of righteousness.
Notice - this is during one more of Israel's many disobediences...
9:32 Wherefore? Because they sought it not by faith, but as it were by the works of the law. For they stumbled at that stumblingstone; 9:33 As it is written, Behold, I lay in Sion a stumblingstone and rock of offence: and whosoever believeth on him shall not be ashamed.
Instead of pouring out His wrath prior to their blessing, at last...
He has ONCE MORE turned from them - in His wrath - that He might do a work among the Gentiles (given the few Jews who obeyed this change/obey it, even now).
Instead of pouring out His PHYSICAL wrath for their having filled up their sins against Him as a nation, He once more merely turned from them in His wrath - for a season.
They, of course, continue to take issue with this finding fault of His.
Worse; they oppose Him on this - note what Paul observed some ten years or so earlier than when he later wrote Romans...
1 Thessalonians 2:13 For this cause also thank we God without ceasing, because, when ye received the word of God which ye heard of us, ye received it not as the word of men, but as it is in truth, the word of God, which effectually worketh also in you that believe. 2:14 For ye, brethren, became followers of the churches of God which in Judaea are in Christ Jesus: for ye also have suffered like things of your own countrymen, even as they have of the Jews: 2:15 Who both killed the Lord Jesus, and their own prophets, and have persecuted us; and they please not God, and are contrary to all men: 2:16 Forbidding us to speak to the Gentiles that they might be saved, to fill up their sins alway: for the wrath is come upon them to the uttermost.
Note the similarity of that with what the Lord had said (prior to the Spirit's, later, largely rejected offer of pardon in Early Acts - based on the Son's Crosswork).
Matthew 23:29 Woe unto you, scribes and Pharisees, hypocrites! because ye build the tombs of the prophets, and garnish the sepulchres of the righteous, 23:30 And say, If we had been in the days of our fathers, we would not have been partakers with them in the blood of the prophets. 23:31 Wherefore ye be witnesses unto yourselves, that ye are the children of them which killed the prophets. 23:32 Fill ye up then the measure of your fathers. 23:33 Ye serpents, ye generation of vipers, how can ye escape the damnation of hell? 23:34 Wherefore, behold, I send unto you prophets, and wise men, and scribes: and some of them ye shall kill and crucify; and some of them shall ye scourge in your synagogues, and persecute them from city to city: 23:35 That upon you may come all the righteous blood shed upon the earth, from the blood of righteous Abel unto the blood of Zacharias son of Barachias, whom ye slew between the temple and the altar. 23:36 Verily I say unto you, All these things shall come upon this generation. 23:37 O Jerusalem, Jerusalem, thou that killest the prophets, and stonest them which are sent unto thee, how often would I have gathered thy children together, even as a hen gathereth her chickens under her wings, and ye would not! 23:38 Behold, your house is left unto you desolate. 23:39 For I say unto you, Ye shall not see me henceforth, till ye shall say, Blessed is he that cometh in the name of the Lord.
He'll Be Back - Israel!
But first Romans 11:25.
It is "in this manner" His delay is playing out.
Read 2 Peter 3 - he also brings up examples from Israel's past as to why their wrath and subsequent blessing at last, had been delayed once more.
He'll be back!
Malachi 3:6 For I am the LORD, I change not; therefore ye sons of Jacob are not consumed.
For "as it is written...out of Zion" that Magnificent "Lion of Judah" will one day "ROAR!" to save His people - the sons of Jacob in Isaac.