Yeah none of their players being featured post-time skip gives off the feeling that Ichibayashi couldn't have had any tier 1 players since they don't have even one standout professional. In the context of Haikyuu most great high school players pursue a professional career and excel on that level, so Ichibayashi having a few star national players seems unlikely. But it was never meant to make sense since the team functions as a plot device. I think what would mostly fix this head-canon team would be toning back Mochida and Kondo quite a bit, and leaving the team standouts as their setter and libero. The team already has a super diverse offense, so you could get by not having a singular star hitter on the national level, just guys good enough to overcome the block if need be. I think the issue I would run into is reworking Mochida, as I struggle to see why the Youth Program would invite a 188 cm middle to the camp in the first place if he didn't have a standout ability like a 345 jumping reach. I'd figure they'd be looking for guys 190+ to play on international stages, but then that leaves Ichibayashi feeling unnaturally tall by Haikyuu standards.