[Question] Lost with CFRU + DPE setup / Leon's Base etc. (Did many steps)

Heyah !

So it's a weird name for a thread, but here's my situation : I'd like to work on a ROM Hack based on CFRU + DPE. I want something based on Radical Red / Inflamed Red with just basic things. The idea is to have all Pokémon on it, some Z-Moves / Mega / Dynamax mechanics, updated stuff to Gen 8 and Raid Battles. That's pretty much it.

So I've started to search around CFRU since I've heard of that for a long time (which is an amazing job). So I wanted to use that as a base. I don't have any ROM Hacking experience, but I've thought I could handle it without too much trouble since I don't want to do a lot of modifications.

But now I'm hitting a wall.

• First I've tried to use the Leon's Base. I've patched it, and nothing really works. When I try to load the editing tools, I get errors, Pokémon names are just moves, I just see a lot of errors that blocks me to go deeper in the edits and the fun. Maybe i've missed a step, but once the UPS are patched, the CFRU + DPE are here and I can mess up with the data itself right ?
• Then I've tried the github method. Did the setup (no issue with that I'm used to this), and then generated the test.gba without any modification, and without DPE atm since I just wanted to see if I could get something working as a first step. As soon as I want to start the adventure, I get a black screen. Solved this.
• I've got CFRU to work as I wanted. Yay ! Now I wanted to add DPE. So I tried to copy / repoint the offsets as said in the guide, but as soon as I start the battle with the Rival, Black Screen.

I'm also confused on how to edit things after. I get the idea that many things will be done with C without too much issues like Wild stuff, but what about marts, trainers etc ? Couldn't find anything.

What I'm missing ? I've read various documentation and I can't really find something that fits these issues. I can provide more informations if necessary.

Thanks o/