I'm looking at doing this now, actually.
Someone will probably beat me to it and, actually, I'm starting with just track icons.
The only danger is that by using internals like this, any update of LogicProX could render such an app completely broken and doing damage. Obviously there'll be a massive disclaimer about backing up LogicProX.
Still my plan is to separately manage the icons (eg PNG) you want, so your custom icons are managed & stored by the app, so that when a ProX update comes, the icons can be applied back in bulk each time.
In time, any such app could probably be smart enough to know whether it's going to do damage and perhaps can be updated using some kind of config instead of releasing a new version of software each time LogicProX updates.
I doubt I'll be able to get it on the MacApp store because of sandbox restrictions (I'm not certain but somehow modifying the internals of another app probably looks, to a Mac, like something only bad people do )