[itsme]

Here's what I usually do with MuseScore exports, applied to your pro_original.pro file:
- open it in EasyABC for further editing
  that requires switching from "ABC file" to "Any file" in EasyABC's file selector box
  (the empty line before {end_of_abc} is required)
- removed V: lines
- changed "^A" to [P:A]
- added %%partsbox 1
- removed I:linebreak $
- added line breaks (CRLF) every 4 measures
  (this is often tedious when lyrics or multiple voices are involved, ideas for a convenient workflow are welcome)
In EasyABC it now looks like that:
   

- saved and reopened in ChordPro App
it looks like this:
   
- added %%stretchlast 1
to get this:
   

- saved and reopened in MobileSheets 3.9.12
  I left fullscreen and changed the window size to simulate a portrait screen
   
  pretty good already
- reduced window height to simulate a page break
   
  missing flat characters, last system cut off, as in your report