Yea, Orleans will be a problem for Waver, but as long as you got Regend Kojirou it won't be. Plus his scalability in the endgame is so high, he's practically still the all-around support than Merlin being buster-oriented.
After Waver, I plan to just spend my quartz in fgo US for Okita, then Jeanne Alter, then Merlin, and anyone else after that, reliving the memeteam in US. My only worry tbph isn't getting the 5-star servants themselves, but getting the 2030 CEs. I've been lucky in JP so far getting 4 copies. lmao.
At the very least I can focus on 3-star servants, something I haven't really done in JP except my favorite 3-star Ushi.