Interesting idea, but unfortunately, I do not think that it fits with the vanilla Original Sin campaign, simply because combat is far too integral. You're proposing the existence of seven different skills competing for ability points. Seven skills implies a much larger focus for crafting than actually exists in the vanilla game. I've gone through the entire thing crafting basically nothing at all.
I think I remember some complaints about the recent Shadowrun game which had skills in it that you couldn't really use often enough to justify it. Will there be any quests can be solved with the Tailoring or Scribe skills?
Splitting up crafting like that will create many new non-combat skills, which carries the false implication that you can get through the game without fighting. In terms of creating new builds, I believe won't be the case, because this change would be reducing the functionality of the existing crafting skill. It encourages different archetypes to divert some of their ability points away from combat skills to crafting.
The proposed system would be better served with a separate pool of points just for crafting/non-combat skills. But even so, what about "Lone Wolf" players? Those players will nee
The main characters history and past is left open, but the only fixed thing is that they are Source Hunters in the field, so the Merchant/Scholar/Nobility archtypes don't quite fit.
There are also some recipes which are ambiguous which category of crafting skill they'd fit under. Sure you an use a bowstring with a bow, but you can also use it with an amulet. So what category does Sinew + Sinew = bowstring fit under? What category does lockpick crafting fit under? Food recipes are a substantial proportion of most of the crafting things, so should there be a Chef skill to put points into?
So, in terms of roleplaying and making sense, the idea might be good. Gameplay wise, it would require a lot of changes, it would be confusing, it promotes crafting skills to an undeserved higher level of importance, it would make Crafting less accessible to Lone Wolf characters. It's another change that would have to be designed in from the start, and can't be added in 10 months later.
