Envy weapons will pick up their FLB the next time Envy comes around. That'll be next January. Which is fine since we don't have dark ult/old ragnarok yet, so we can't even farm up some dark regalia yet.

You max out at 1 orichalcum if you can't possibly beat the whole thing. The second week's set of missions changes up to only have 4 more points available that don't require clearing, so that's a total of 9 over the two weeks. And you'll need 10 for that 2nd ori. If you can manage to clear the quest entirely at least once and satisfying a mission or two, you should be set for the 2nd ori. Funny enough, if you don't have a fantastic team for a particular element, the 3+ SRs or below (as you need 4 SSRs to push you out of this one) is probably the requirement you satisfy just by walking in with whatever you have. And for Crom Cruach, a mission asks for 3+ Attack types, and that's the most common filler type as far as I'm aware of.

If you're fine with just 1 ori every 2 weeks, then you only need 6 points. You can pick up those through:
1st week: Challenge 3x, Challenge 5x, Clear 1st stage 3 times, Clear 2nd stage 3 times
2nd week: Challenge 5x, Clear 2nd Stage 3 times

That does emphasize at least making the attempt every single day you can. And honestly, if you're aiming for just those 6 points exactly, and you need it, just go ahead and burst through stage 2.

Beyond that... if you're basically set on 10+ points, the next question is if you should really bother for 18/20 or not. Forget about the grimoires at 12/15, we get enough of those elsewhere. If you can clear the quest but absolutely needed luck to do so (like me), just settle for the 2 ori at 10 points. I can't clear with Arthur this week. I won't be able to clear with Joan next week either, as I need Andromeda's heals for my setup to get through. I don't think I can clear with 3 R's. Or clear the last stage within 15 turns. Or be able to clear with making sure I have at least 1 of each type in the party. I don't expect to be able to hit 18 points, so I'll probably just relax next week and pick up the ones that don't require clearing.