What does HIs understanding is infinite mean to you? Is it of some things or all things?
This is still eisegesis by way of leading questions.
You are not making an argument from Psalm 147:5. You are asking questions designed to smuggle your interpretation into the phrase “His understanding is infinite.”
The verse says God’s understanding is infinite. Amen. I affirm that.
But you are defining “all things” to include every future free act as an already-settled fact. That is the very point you need to prove, not something you get to assume.
God understands all reality perfectly. If a future free act is not yet a settled reality, then God understands it perfectly as what it is: a real possibility, not a settled certainty.
So again, Psalm 147:5 teaches God’s infinite understanding. It does not teach that every future free act already exists as a settled fact before it happens.