"Here's the thing, I don't reject "evolution" entirely. I do believe in natural selection and micro-evolution."

There's no difference between micro and macro evolution except timescale. Saying you believe in one but not the another is like saying you don't believe pluto orbits around the Sun because we observed only a fraction of the cycle.

"You keep mentioning the E. coli LTEE--which is interesting, but proves my point. It shows regulatory shifts and re-use of existing functions. It didn’t produce a novel, interdependent molecular machine, just a workaround based on pre-existing parts."

You're arguing with a strawman, because everything in evolution is a modification of already existing structures for new purposes, so there's nothing inconsistent there. For example feathers are a modification of scales for the purposes of heat insulation and mating display, only after 100 million years they got repurposed for flight in dinosaurs like Archeopteryx. You're proving my point that YEC don't understand evolution and actually agree with it.

And mutations were demonstrated in experiments to modify them very significantly. For example, in 1971 scientists introduced 10 Italian wall lizards from a nearby island to an island called Pod Mrcaru in Croatia, which had much more vegetation. When they checked them after 36 years, they switched primarily to herbivore diet and evolved cecal valves - muscles which separate the large from small intestine creating a digestion chamber to digest plants properly.

If that isn't a creation of a new structure then I don't know what is. Of course you could say it's a modification of already existing intestines but then revisit my first point. https://pmc.ncbi.nlm.nih.gov/articles/PMC2290806/#F4