Let's talk for a second on some work-arounds for these issues using OpenCore

Inside of OpenCore settings (I'm assuming you're pretty comfortable with the OpenCore UI by now), head to the "Root-Patching" tab. Under the "Non-Metal Configuration," you can activate things to make your Mac run better.

Dark Menu Bar - This changes the text color on the menu bar depending on the desktop background. (Beta Menu Bar must be enabled for this to work.) (Also, by enabling Reduce Transparency, Dark Menu Bar does absolutely nothing.)

Beta Blur - In some application windows, the sidebar has that nice translucency blur. If your window seems to act weird, try toggling this and see which one works better for you. (Also does absolutely nothing with Reduce Transparency enabled.)

Beach Ball Cursor Workaround - Supposedly this makes the loading cursor actually spin (though this has never worked for me).

Beta Menu Bar - This is a custom built menu bar. It changes colors and rounds the edges for menu items just like on a native Mac. (This is the one feature that is still in beta, it has been in beta for years now. If you have issues with the menu bar, disable this.)

Disable Beta Rim - Honestly, I'm not entire sure what this does. My Mac has acted the same both with and without this checked. But, I believe it adds edges to the windows so they look more like a native Mac. If someone else knows, drop a comment down below because I'm not entirely sure.

Disable Color Widgets Enforcement - In macOS Sonoma and Sequoia, you can add widgets to the desktop. If the colors do not change while looking at the desktop or an application, you can check this. This gives the Mac one less thing to do. If the colors to change, you can leave this unchecked so the UI is nicer.