Thanks for the input. Let’s see if I can summarize.
jQuery Modile - Do Not Use - based on obsolete jQuery 2
Bootstrap 3 - Avoid usage
Bootstrap 4 - Can be used with jQWidgets.
jQuery 3.x - Can be used
George has mentioned there is a new version of AppStudio coming very shortly which solves the Google Play Yellow Flag. But I assume that a simple recompile when this new version is released with remove any Yellow Flag issues.
jQWidgets - Can be used, but has a fee for commercial usage. Works with BS 4
Common Controls - Can be used.