There is the github issue at https://github.com/le-doux/bitsy/issues/5 and also there is no definition of who keeps what intellectual property rights over created content. Please consider that for example Activision Blizzard receives the full copyright for everything that is created with the map editors of their Starcraft and Warcraft strategy games according to their respective EULAs just to spite anyone that might want to do a straight port of something they created in those editors to some other platform and sell it. Bitsy not having a licensing agreement that states rights and responsabilities is just a horendous thing.
For the record: Do I have the intellectual property rights over the graphical assets, logic control flow, story that I create in Bitsy? Do I have intellectual property rights over the html file that is exported by Bitsy? Can I stick the file into a SuperSmartTranslatorTM and get something that I can legally sell on any games distribution platform or store?