Yeah, camera its the biggest issue in Defold. In my project I am using gui nodes instead of gameobjects to avoid the problems of the camera.
I think the biggest improvement for defold will be a native 2d camera (not a library), with X and Y parameters for the viewport, and other X and Y parameters with the objective Resolution, with this, people with low pixel assets can work with , for example, 300x200 window size, and if he put a sprite in the lower right corner, then He knows in all the computers the users will see this in the same position, but in his Objective resolution.
a function for moving the camera, zooming, and a getter for the x,y of the object, and the click in the screen.
In those months using the engine, this is the only problem that I found.