Hey there! Currently you can import only individual textures. I did this because in this way you can make sure to define your own unique IDs for every texture and you will not be conditioned by the randomizig IDs set in a spritesheet for each tile.
I decided to do it this way because it was the easiest to work with in the end product for me and maybe for other people too. At my end I import each object individually having unique IDs.
To be honest here, I had plans to think of a way to import .png spritesheets while also defining IDs for them, but I have a few other more important features in mind like duplicating chunks of map / exporting and importing them on other maps, automatic defining IDs for all the undefined textures in the assets folders and so on. But I will take your question into consideration and when I will have some time I will think about it:)
Thank you for your question and feel free to comment at any time:) I will reply
