I don’t see anything new here 
The GPS stopped working thread is initally about the XA2, which cannot connect to a SUPL server without suplpatch, because it has no certificate for the secure connection. So your settings were already tested and do not work on the XA2.
And many people claimed that they don’t wan’t to use A-GPS, because this does not fix the initial problem.
Also SUPL only works with mobile data not when connected to a wifi network.
All other settings you posted are already known.
A simple summary, that’s the novelty. 
The patch exists so the XA2 users should be happy.
This part is not clear for me
I can understand that they wish to use ‘device only’ mode because privacy concerns but I did not get that the GPS was previously working indoor without A-GPS. Is it a specific problem of XA2 or a general problem? Considering that I have a X10II, it might be a general problem.
Without changes was working well with a WiFi connection over fiber probably because such a connection was able to sync the system clock precisely enough and obviously this require the autoupdate of time/date set.
With these changes is working with a mobile 4G connection + UDP VPN, also. So, from my PoV is a great advantage because now I can have indoor GPS quickly working with my mobile connection. Which was my goal.
Quite a late reply, but maybe could still be relevant. In my experience, that “something” is giving the module the permission to allow it to access location at all times.
I can´t find to tick…" grant it signature spoofing using the " enable system package replacement " permission
For the PlayStore advaced tips…
Can anyone give me a clue… Thanks
Is that the one in Settings - System - Android AppSupport, which you check to allow the replacing of system packages with their unofficial versions?
I thin its the same… but with different name…
Thanks