Root (moving stock apps to ROM)

[mgmueller]

I've rooted my Nvidia Shield Tablet.
Mainly because of the annoying update process for the stock apps.
Maps, Google Plus and the likes get updated frequently. The original in the ROM gets deactivated and the update in user memory gets activated.
Via root I can copy the update to ROM, thus replacing the original.
In general, this method is working fine.
I only have 2 problems: Google Maps and Google Plus.
When using Apps2ROM, I get a warning instantly: Might not be working.
Whether I use Apps2ROM or Titanium Backup, the result is the same: They work for some time, but after 2 or 3 restarts they keep crashing.
Any ideas, why this is happening? And only for those 2 apps?
When fiddling around, I had an installation, which did allow for one of the two in ROM. But as soon as I moved the second one to ROM, both crashed.
(I have no idea, how I've got to this installation. Now I can't make it work again and neither app is working in ROM.)
So there seems to be some "interaction" between those 2 apps?
Anyway...
For now, I have both apps in user memory. I can live with that, but the preferable solution would be: All (stock) apps, that had been in ROM originally get their updates moved to ROM as well, thus replacing the original...

EDIT:
I'm at the stage now (both on NVIDIA Shield Portable and NVIDIA Shield Tablet) where I had been before:
I can move one of the 2 apps (Google+ and Google Maps) to ROM. But as soon as I move the second one, the other one starts crashing.
What's the link between Google Maps and Google+?