currently you can not import tmx maps, however, we are investigating to support Tiled. Please also post your request in the roadmap post, so we can see if more developers are interested in that.
As an alternative to Tiled, you can also use our own level editor functionality. The Felgo level editor has the advantage, that you can create levels also on your mobile phones, and once you released your games can let your players create own levels and share them with other players! So user-generated content is really easy to achieve with it.
For examples how to use the level editor, see the game Squaby or Blockoban. The 50 levels of Blockoban were made with the level editor, and both games let you create levels on your device. Also, there is a full tutorial how to use the level editor in your game here.