I think they wouldn't need to necessarily reinvent the wheel with captures. If they just included a NAM block, that would probably be enough. That's all the Anagram has done on the capture side.
Hiring a UI designer would be a great help, and yes, the apps are all a bit shocking. The load time from selecting the patch on my GX-100 to showing it on mobile/computer editor shouldn't take 10/20 seconds. I don't know what protocol they're using to transmit the data, but it needs to be modernised.
I think that they do get so much right with the functionality though, like the options to assign any parameter to any control and the properly seamless preset swtiching. More assigns would probably be on some people's wishlists. Oh, and the wavetable and input assigns to parameters is great too.
I personally think that their amp sims do leave something to be desired. I've never been totally won over by them and struggle so much to get them to sound like I want to that I've kinda given up with them. Compared to something like the cheap Sonicake Pocket Master that I've got, where the Twin sounds perfectly useable to me with a few tweaks, the one on my GX-100 just doesn't have the same ease of dialling it in.
Adding a good synth would be a good selling point too. And maybe getting all of the effects from the Plugout might be a USP for them? Give it all to the users of the new gen pedal.