Thanks for your reply. This was the main issue that was preventing me from using the iOS app. I am looking forward to giving it another go! 
The lack of a revision mode and colours in dark mode would be nice to see in updates, but I understand that the team don’t have the resources to address everything.
I know there is always a workaround using styles instead of revisions that I can use:
https://forum.literatureandlatte.com/t/revision-mode-on-ios/33948/10
Many thanks.