Hi there - love Tiled, using it heavily right now. I do have a very specific suggestion though:
When working with large isometric maps, it would be super helpful to have an optional view (not unlike the minimap) that shows the effective tile-grid from a top-down perspective, even though the map itself is isometric.
As an example, similar debug view I have in my actual game after loading the isometric map, where the black is a ‘walls’ layer:
Wouldn’t even necessarily have to have the actual tile textures on it - but maybe e.g. colours per layer or similar.
Being able to do this is really helpful if e.g. you have tiles that have collision areas, because sometimes the isometric perspective is misleading compared to where the tiles ‘really’ are from a grid PoV, and you are unknowingly placing tiles in the wrong position (e.g. at a diagonal).
I know this can be sort of achieved already by switching the map between Isometric and Orthographic mode, but it distorts the positions of objects, which makes it much less useful (as well as being ugly)