Selection, looping, cursor starting point - center of the project throughout all views, zooming, scrolling, transport behavior should be viewed as a whole and be done in one sitting. Otherwise it will be a mosaic of patches that might or might not solve underlying issues.

Personally, I believe a big chunk of solution would be to implement a timeline with proper cursor instead of "song overview" that would be persistent through all BIAB views. That cursor, when set, will determine new project center and will return you to that position. Panning and zooming should respect new project "center".

Selecting a part of any track, should duplicate selection on timeline - that is a standard approach, not re-inventing a wheel. That selection could be used to define loop points. Alternatively, a selection could be made on a timeline itself, which would duplicate selection globally - same selection on all of the tracks. This could be very useful not only for "looping" but for other tasks as well. (see video below)

A single global looping button at the transport (the one we already have). The deeper options of repeats, etc should be achieved through right click of same looping button - this is already done, and if there are some particular looping settings in other parts of the program (6 methods) they should be brought to same looping button context menu.

Bottom line is that I rather see certain things done in a fashion of accepted standards than patching smaller holes.
Piano Roll "almost" got the standard timeline going with the selection option (see Jeff's first video), but it is very finicky and the problem of inconsistency doesn't go away, even if it is brought to standard (proper cursor / start position marker, loop selection without hard coded automation of ON state, disabled only through unmentioned shortcut), we would need same timeline in all views.