It's actually the commit before that (support for gba irqs during rom reads) that improved many games. But yeah many improvements. Flicker in f-zero and Mario kart super circuit is also gone for example. And the mother 3 textboxes no longer flicker.
Button mapping has not been implemented yet for gbarunner3, but is planned. I'm not sure what you want to know about hicode, but there is a branch, and it is not merged yet. I don't speak Spanish btw, so English is sufficient.
Doesn't it take way more time to boot the home menu in the first place, than to boot into a luma payload? Maybe there's a way to set a key shortcut you can hold at boot or so?
Good to hear you like gbarunner3 so far.
I would like to note that I'm the developer. Not Robz. In any case, rfu and hicode are not ready to be merged yet currently. They will likely be further developed at a later point.
Nice to see you're still around as well. Gbarunner3 has already achieved some major compatibility improvements compared to gbarunner2, so you're probably going to like it.
It is still possible in gbarunner3 to disable center and mask, but it cannot hide the offscreen area, just like gbarunner2. There's already a hicode branch that might work for some Pokemon hacks. But it's still a troublesome thing.