When I say an "edit mode" I don't mean the ability to add individual houses or anything I mean the idea of having a tool that lets you add/destroy districts, farms, greens, citadels, castles & plazas, I feel like in doing so this map tool would be elevated to a higher quality (I think that if this were to be added a "zoom" feature would need to be added also to account for adding more stuff tho)

Some time ago I tried to make an application that allowed something like what you requested: City Painter. I didn't like the result, so it hasn't been developed any further, but one day I'll try to implement it differently. 

I played around with the Painter for awhile and I agree with your statement from back in 2020 " Painting doesn't feel natural. It is slow and uncomfortable." and while I agree, I made a small town that I think looks quite nice, I hope that one day you do re-visit the project and flesh it out a little more (perhaps Townscaper esc selection of assets with the ablility to zoom in and out with the ability to change sections of the grid) but perhaps you never will return to it if that's the case, you do you
Kind Regards - Twig