Even if you do a research about x game engine, there's always bumps in the road. 2 years ago for a release in the previous studio I was working for, when Unity switched version to 5, a lot of plugins specially for rendering were broken in the process. There's always issues that you can expect and there's always a way or workarounds. In the case of engines like Unity and Unreal there's a reason why you can obtain source code now.
But to be honest, personally I don't see the issue, I mean, if Scirra can't offer export to consoles, then you change projects. In the world of indie dev you can't just stay with one product just because you are an artist and can't code. I'm an artist and yet I learned to code. Necessity pushes you to it, that's all. is not the first time a dev quits Scirra to change engine.
Slain which saw a major release was a C2 project and yet was forced to change to Unity. Engine was simply too limiting.