Huh, strange.
I accidentally messed up my previous setup and had to reinstall the whole thing, but I did see what worked this time.
It worked with the GOG version of the game, so I guess I did something right. :D
So what I did was: download DS1 and DS2 via GOG Galaxy, download the Legendary mod, the AllSaves mod just in case, and the Elys DS2 Succubus Manager from the Nexus and the Broken World Fix from the Pastebin link (link 1:
https://www.nexusmods.com/dungeonsiegeii/mods/4 ink 2:
https://www.nexusmods.com/dungeonsiegeii/mods/23 link 3:
https://www.nexusmods.com/dungeonsiegeii/mods/28 link 4:
https://pastebin.com/Gcg9qLLp ).
Then I installed the Legendary mod via the downloaded installer directly to the DS2 folder, manually copied the files from the Broken World Fix to the game folder, placed the Elys Succubus installer into the game folder and directed it to said folder, ran the "Reg Patch DSII" file twice and pressed 1 and 2 each time and I had to download and place "shfolder.dll" (link:
https://www.dll-files.com/shfolder.dll.html ) into the game's folder.
After all that was done, I ran the Elys program and had it in windowed mode (full screen might work as well, but I don't have to restart the computer in case the game doesn't load up), left the resolution option on "normal" and clicked the Broken World icon in the Elys program.
I have no idea why it works, but it does and I think I've managed to pinpoint the needed steps now. :D
Might be the installation path didn't go right at first, not sure.
Edit: I think I've found the culprit for the menu being uncooperative when the game refused to move from the character creation screen, it's the Menu Fix optional mod you can install with JSGME mod manager that comes with the Legendary mod.