When facebook released React it released it with all sorts of provisions on the license eventually it realized that opensource expectations are of permisive licenses, and GPL is yesterdays expecations now days Permisive ( perhaps with GPL compatibility ), I think the general expectations are for MIT or similar. MIT is very simple and compatible to use and contribute.

Facebooks 'React' license

https://github.com/facebook/react/blob/master/LICENSE

Modern Game Engines for 2D and 3D, notice there is an expectation among modern game developers use Unity OR something with permisive license:

https://github.com/Kode/Kha/blob/master/license.txt
https://github.com/armory3d/armory/blob/master/LICENSE.md
https://github.com/HeapsIO/heaps/blob/master/LICENSE
https://github.com/openfl/openfl/blob/master/LICENSE.md
https://github.com/HaxeFlixel/flixel/blob/dev/LICENSE.md
https://github.com/openfl/away3d/blob/master/LICENSE.md

Really no point in releasing another 2D engine if it's old school opensource only, there are plenty of good tools that are MIT.

Please note as a Haxe user I have no specific interest in Corona, seems there are already very good solutions that are better licensed - Heaps, NME, OpenFL, Kha to name but a few. But since Haxe compiles to Lua it might be interesting to take a look. My point is that I think it's a shame to go to effort of cleaning up code for opensourcing and then going halfway, better to release most of it and then charge for components, but it's your choice if you want to attract developers.