Servants for Arts/Crit Team

Get you a Tamamo. Or use a support Tamamo. Renders the CD times on saberlot's skills irrelevant. Other that yea your best comp still would be running saberlot with double support as long as you have 2030. Special mention goes to Hans if it's grailed and has his crit up skill at 10. Or waver for the same reason and well being a better Hans. Helena is ok as a hybrid support but can't provide the crit buff either of the other 2 can (and has inferior steroids since it's on a slightly longer CD than the other 2's steroids) but she does decently. But yea, you could go double dps and one support but don't expect the second dps to do much critting or act to its full potential.

Also typically 25+ stars a turn is enough. If you want overkill bring Hans for 9 more stars :p

Saberlot is pretty self sufficient. You can have Andersen, Helena or Halloween Elizabeth to support him. The only problem I see is when you switch to Chloe or other attackers you might not have enough star.
Getting a 2030 definitely solves the problem. I would also suggest watch for caster gil this December. He is very useful in arts crit team.
And of course, Tamamo is a must for all arts team.
I would also consider Li Shuwen, since Saberlot is going to be terrible against archers, though his skills only last for one turn

Another great addition to an arts crit team would be Mozart after you unlock his 3rd skill from his Strengthening quest. At level 10, it generates you an insane amount of stars (50 IIRC), so he's another option you can look at as well. He also has an Arts buff skill as well so he's just all together a really solid support servant for the comp you're trying to run.

I’d suggest using Hans instead of Helena since he fits better in crit teams and Helena stargen has a 10 turns base CD while Hans’ is only 7. Dont even think about using Vladdy ( Vlad + Daddy , get it ?) in Arts Crit unless you throw Seal Designation or Leisure Stroll on him. Chloe can provide about 36 stars with Kiss Demon activated and a QAA chain. One more thing about Helena, make sure to use her awesome 6-Hits Quick if you decide to use her as a support.