text: Yes. You've mentioned that you are doing this with an iphone. 
  
  I don't understand why you would limit yourself too *only* using the app in your iphone. Unless you don't have a computer at all. 
  
  Choosing to only use maps.me to do all your editing is really a handicap. 
  
  The changes you make via the website will make it to your offline maps. And, I think, just as quickly as edits you make via the app.