Flatpak override doesnt seem to work with colon in path (steam deck)

Not quite sure whether this is the correct place for this issue.

Running this on steam deck's konsole in order to be able to install directmusic and directplay into "Rise of Nation Extended Edition" (in order to attempt to fix ingame audio) ...

```
flatpak override --user --filesystem=/home/deck/.local/share/Steam/steamapps/compatdata/287450/pfx/dosdevices/c:/windows/syswow64 com.github.Matoking.protontricks
```
brings up following error basically:

```
F: Unexpected filesystem suffix /windows/syswow64, ignoring
```

and since this path is being ignored by flatpak override... protontricks / cabextract cannot access it

```
Executing cabextract -q -d /home/deck/.local/share/Steam/steamapps/compatdata/287450/pfx/dosdevices/c:/windows/syswow64 -L -F dmband.dll /home/deck/.local/share/Steam/steamapps/compatdata/287450/pfx/dosdevices/c:/windows/temp/dxnt.cab
/home/deck/.local/share/Steam/steamapps/compatdata/287450/pfx/dosdevices/c:/windows/temp/dxnt.cab: WARNING; possible 5960 extra bytes at end of file.
/home/deck/.local/share/Steam/steamapps/compatdata/287450/pfx/dosdevices/c:/windows/syswow64/dmband.dll: Permission denied
```

Full error log:
[log.txt](https://github.com/flathub/com.github.Matoking.protontricks/files/9411206/log.txt)

I also tried flatseal with the option of granting access to all user files, even host files, no avail.
Could it possibly be that flatpak needs to know the exact path protontricks / winetricks / cabextract will try to access later on ?