I think going open-source has to be combined with a complete re-brand and perhaps target a slightly different market.
Corona as a name hasn't struck a chord, it's too closely associated with the beer, surely the first result for your own brand name should be for your product, not a beer, pictures of the sun or a band.
Brand awareness is poor. Very few industry professionals I've spoken to have heard of it, if they have they haven't tried it or considered it as a serious option. I listen to a lot of dev podcasts and have only heard Corona mentioned once, in passing, and this was by a guy who was still building flash games for a living and therefore the perfect prospective customer....
As it stands, while targeting pure 2D game development, its direct competitor Defold has big backing and credibility from King that it's almost impossible to match. Making Corona open-source is a way to differentiate from Defold, but you still need to be out there and visible, at all the developer/Linux conferences in North America, Europe etc. getting it in front of people and engaging the wider open-source community.
A pivot away from purely being marketed and focused as a games engine might be an option. There's still no industry-standard cross-platform mobile app framework, as opposed to Unity3D/Unreal in the games arena.
Xamarin, React, Flutter, Progressive Web apps, Ionic etc. all have their plusses and big minuses and many firms, while using these technologies, are always looking around for something better. The Corona Simulator is a massive feather in the cap given the speed of iteration it offers.