I've seen this a few times. The key limit is that once drawn the characters are set, you can't move the drawn objects around. What I'd like is something like drawio for ASCII/Unicode. I've been thinking of writing my own for years, but that'll probably never happen so I'll just keep mentioning the idea when similar apps come up in the hope I inspire someone else!
Perhaps I'm misunderstanding you but this tool expressly has a select and move tool.
It does, but that selects and moves the cells not the objects and then redraws the cells? Actually, going back to have a play I see that it does allow some modification of existing objects but it isn't terribly flexible.
I've just done a quick search and found one that I've not spotted before, which is a bit closer to what I want in that one respect, but not nearly complete overall (and not seen a check-in in 8 years): https://textik.com/ - that might illustrate the key difference that I see missing in asciiflow.
