Accepting that there is room for improvement and proceeding to look for ways to achieve that are a good step forward so you've got my respect for that.

I similarly struggle with memorising longer fights, the best solution for that is simply post it notes and a second screen. I'll write myself out a very basic sequence of what the mechanic actually is rather than the obtuse ability names the game often likes to use. That then gets stuck on the main monitor's chin until I've got the fight down.

As far as improving goes, going by the analysis links, the biggest thing by far is to simply get into the habit of keep that GCD rolling. Don't over think things, don't sweat it about perfect dot uptimes or anything like that at this stage. Just press something. Once you have the motor muscle memory of keeping that GCD rolling and the rhythm becomes second nature you'll have a better baseline to build from, this will make it easier once you start focusing on doing a better job of pressing the right button for each given situation.

TLDR: Fight notes on Post-its under the monitor to jog the memory with what's coming up next. Press more buttons, don't over think, just press.