This medley of suggestion consists of easy and small details that can be good in Platform Builder, here we go:
Tileset name: When you have multiple tilesets in a game; when one is selected, will be cool to have below the "Different Tileset" button, the name of the selected tileset.
Select the enemy range: Any enemy that interacts in his movements or actions with the player, select a range to do them. For example. Range 5 means that the player needs to be minimum 5 blocks near the enemy to execute some stuff. For example, an enemy that moves left and right normally but when the player gets 5 blocks near (this depends on the range) it will start to chase it, or shoot he/she or anything you want.
Add player death command prompt: Add an option to add commands that execute when the player dies, and execute them before the player starts the animation of dying.
Export character sprite-sheet customized: If you have created your own design with the design creator, you can export it, for example.
A complete sound manager: If you can do this with music, why sounds have a limit of 30?
Disable and enable jump: As it were wall jump or super jump, in character editing, disable and enable jump.
Move moving platforms with commands: Move a moving platform with a command, I think it will be cool.
Teleport instantly to the checkpoint when the player dies option: Instead of the animation of dying.
Likes and dislikes in games in explore section: I like this idea.
Expandable command blocks: To select all the range specified for a command block to execute
Player teleporting: A command to teleport the player as the warp does or instantly.
Repetable command blocks: Make a command block that can be repeated multiple times or infinite times depending on what you want, for example, EVERY TIME I pass through that command block, it will execute the commands inside and not only once, and select a timer for uses and a limited quantity or infinite.
Thank you very much for reading and happy Platform Building