I think it depends on what you mean by "cheap foreign engineers." I am born and raised Canadian. I make a decent chunk less than my American counterparts, even when working for the same company. Not because they are necessarily better suited for the job, but literally because of the country I live in. The same is true for engineers all over the world.
So yes, companies absolutely can get cheap(er) labour and have the same, or at least similar, quality.
That is just saying that they will be giving some donations to the project. I have zero insight into W4 or the Godot Foundation, but they may have already donated. They don't claim to be the sole financial contributor to the project.
So yes, companies absolutely can get cheap(er) labour and have the same, or at least similar, quality.