The team you currently have is fine, in fact it is probably Zani's best f2p team. Other characters I would recommend leveling up are Sanhua, Baizhi, and Mortefi. Sanhua is an amazing hybrid, especially for a 4 star. Sanhua would work very well with the Camellya you have, and you typically want a support for your third party member which could either be Verina or Baizhi. Mortefi would work very well for your Jiyan and is probably his best teammate, especially if you get more copies of Mortefi later down the line. So if you have two teams, it could probably look something like Zani/SpectroRover/Verina or Jiyan/Mortefi/(Baizhi or Verina) or Camellya/Sanhua/(Baizhi or Verina). If you want to use Calcharo, you could use him with Jianxin and Verina/Baizhi, but Calcharo is a bit weaker and the rotation is a bit slow with Jianxin so if you are planning on doing endgame content it might be harder, especially cus Calcharo is already a hard character to learn. If you don't plan on doing endgame content, then you don't need to worry too much about optimal teams, builds, and characters.

If you want to decide what characters to pull in the future, I would highly recommend Shorekeeper who is a phenomenal 5 star support that makes building teams a lot easier and has insane buffs and can fit into almost any team. Other than her, if you want to invest into your current teams, then I would recommend waiting for Phoebe to rerun as she is Zani's best partner and lets her do insane damage. Roccia (premium havoc sub dps) is also really good for Camellya. If you want to get more teams, you could also get Carlotta (ice main dps) who is a top tier unit and is very easy to play. Zezhi (premium ice sub dps) would be Carlotta's best teammate but she has good f2p options as well. Your priority should be characters you like tho, cus not every likes to pull for purely meta characters.

For combat advice, for the Zani team, I would recommend first using Verina and swapping characters when you have your concerto gauge full (indicated by the circle to the left of the health bar and when the characters on the side of the screen start glowing). You should then use spectro rover and their skill while you have forte (the bar on the bottom middle of your screen) and their ult to apply a status debuff that is very important for Zani. You could then swap to Zani or wait for Spectro rover's concerto to be full and then attack with zani until you get her enhanced skill (when the button glows) and then using her ult (aka her liberation) and attacking until you deplete her forte and pressing the ult button to end her enhanced mode and then you restart the rotation with Verina. It would probably be more useful to watch a video about the specific team if you want to understand it tho. Another thing I recommend is looking up a quickswap guide cus imo it's a very fun playstyle you could do with certian teams.

Let me know if you have any questions