Would not it be good also compress the tileset?

Hello, I would like to clarify a question, the tag data date of tmx are compressed by tiled to decrease the size of the right file? My map has many tilesets, if this sort of compression existed in tags tilesets could reduce the file size? This already exist in the tiles?

For reducing the size of the entire file, you could just use regular compression, for example gzip the file or put in it a zip archive.

This would be done as part of the deployment of your game, since Tiled needs the maps to be uncompressed.