I’m not familiar with how GW works, but if your going to upgrade CFW, just upgrade to Luma 3DS. Im on Luma 11.2.0 and i can play both Mario maker and Moon. And as for installing it, i had Reinand before, and all i did was drop the Luma files on my SD card, and after the initial launch config, it worked flawless. Like i said, since im not familiar with GW im not sure all the steps you’d have to go through, as im on A9LH with Luma CFW. Good luck man.
what 3DS you was tried? on my O3DSXL Pokemon Sun/Moon and Mario Maker working fine, pokemons U + patched , Mario Maker E + update for eshop , emunand updated for newest one 11….. probably you was trying on N3DS…..