Nastia Liukin constantly changing her routines to keep gaming the code better with each passing year is what resulted in her winning all those Olympic medals, actually.
The degree to which people had to change their routines in general for 2006-2008 shows that MUCH more adaptability is possible in a short amount of time than might be assumed. With life in general, people are capable of more change than they think, when they actually try to do it rather than staying in their safe/lazy zones. The coaching culture of sticking with the status quo is an issue.
Anyway about the FTDB…it’s a FTDB. Shilese was doing it fine a few years ago and seemed to change to the Double Front just because of other routine changes and her coach thought that dismount sequence was the best way to get reverse grip in. I don’t see her current dismount saving any deductions, just opening her up to higher leg separation (also risking dismounting too close to the bar). Maybe there really is some other reason she can’t do the FTDB, an element that nearly every gymnast at this level is capable of doing if their life depended on it, but I put the odds of that as being very low.
It does seem the Double Front 1/2 could be an improvement for her, she’s shown it perfectly in practice, but then why isn’t it being pursued more urgently? The same can be said about her Stalder Nabieva; the ability is clearly there and Paris Cup was the perfect place to be putting it in, but an attempt was not made. Keeping that Toe 1/1 in its current place in the routine is simply an admission of setting someone up to not progress; you can’t be planning that pirouette before such a difficult release if you want to maximize your chances. It would make far more sense to open the routine with Toe 1/1 + Stalder 1/1, so then the way can be clear to aggressively go after the new release (and to properly connect out of it, with not just the Pak, but also hopefully the shaposh afterward).