RPG Maker XP and later are very flexible because you can actually use code and modify major parts of the game engine (you're limited mostly by the actual editor). But yes, in RM2K/2K3 your ability to break away from the standard JRPG framework is much more limited. Regardless, I've been surprised in the past with what people have been able to achieve within those limitations. I haven't played Ultima VII but I can't imagine it's completely out of the question, it just might require quite a lot of "innovation".
Thanks for this! I've also been learning Spanish (for a while now) so I'm always on the lookout for input/practice material. I have a lot of nostalgia for RM2K/2K3 and the 16-bit era of RPGs, so it would be cool to check these out sometime.