Although a tilemap collision mask object has been implemented in GDevelop 5.0.139, your extension works way better for me. I was having an issue with lateral collisions where sometimes the player slides one pixel inside the GDevelop collision mask object, although it never happened when colliding with platform sprites. The gameplay felt unpolished because of that. With your extension, my problem was solved because it allows me to use a sprite with platform behaviour as a hitbox, so the collision issues are gone.
You did a great job developing this extension! It made everything easier for me to make my game.