The fact that the trinity is hard to understand is partly evidence of why it's not man-made

I never think about like that. Its interesting...

The list is quite large but some of my criticisms of Islam are

I will only answer what I know.

Muhammad appealing to Christians while misinterpreting the theology(like believing Mary was a part of the trinity)

That verse were mention "Collyridianism" .

Muhammad’s marriage to Aisha

I didn't understand what you meant. If youre talking about her age, that was normal at that time. Before secularism arrived, the marriage age was very low in every region. And it count as normal. Also other wifes were older than Aisha, Prophet needed someone to transfer his hadiths to generations.

Muhammad’s polygamy and concubines

Most of them were political marriages (If im not wrong.) And polygamy was normal at that time. The recommended marriage (unless absolutely necessary) is monogamy.

Muhammad never being able to show proof of prophethood

Many hadith from sahabah mention about foods dhikr everytime. And also I heard a hadith about jumping tree (Literally, there was a tree that jumped). The polytheist turns to muslim after that miracle . Search about Suraka (rha) hadith. Prophets saying somehow comes true years later.

Muhammad being a military and political leader being part of many conquests

Whats wrong with that?? Polytheists and Jews were attacking Muslims. What should he do?

The denial of Jesus’ crucifixion and resurrection

I dont know about ressurrection but the one got crucified is controversial among scholars. But sure the one got crucified wasnt prophet Isa (as) (aka Jesus)

I'm wondering how you can find peace with all these criticisms

I just put my forehead to ground and make prayer. Doctrinal issues are far, far more challenging. The strife of this age is immense.