My pleasure.
Would you perhaps like help with the import/export system you originally had in mind?
It just so happens that I work as a Software Engineer, and I regrettably have made my own experiences with the shortcomings of HTML5.
If so, let me know what worked and didn't, and what specific things you tried that HTML5 stopped you from doing, and I'll see what I can do.
Regarding the game speed, that is understandable.
Perhaps calling the next wave early could be a consideration?
That would allow you to pace the game faster, if wanted, while not heavily interfering with any existing systems.
Assuming the waves aren't handled in a big for loop lol.