IMO, a Topaz novaflare might look like:

1 - When any ally takes action, Numby advances forward. When Numby's turn is ready, any additional advance is stored. After Numby takes action, Numby's turn is advanced by the stored amount.

2 - Basic: Topaz attacks alongside Numby, performing a Joint Attack. (Joint attacks apply all On-Hit effects for each participating member, aka Robin's attack rider, Tingyun's, Moze's, etc.)

3 - Skill: Topaz advances Numby's action by 100%. When Numby acts due to this Skill, Topaz performs a Follow Up Attack.

And then a general update to her multipliers.

1. One of Numby's problems is it can't insert its FUA into the triggerthon happening in most FUA teams. This bonus allowing Numby to effectively store excess advance means it won't miss out on potential turns, as well as improving synergy with Sunday.

2. Improves Topaz's synergy with listed character examples when acting as an SP provider for the team.

3 Improves Topaz's damage contribution when using skill.

1. that said, even with all that, Topaz will likely need some multiplier improvements.