Is my roster enough to clear 6.4 SO fearless?

Nefer + Lauma team, Ineffa + Columbina wheel chair with Neuv, Skirk team, Mavuika team

Yeah, you should be good. Just farm artifacts if your struggling.

Yes.

Yeh, you have:

Skirk, Chef, Furina, Yelan/Ayaka for SSAO.

Mav, Citlali, Venti/Kazu, Benny for Mandragora.

Clor/Neuv, Bina, Ineffa, Xilo/Sucrose for Duckle.

You won't need Flins for 6.4. You can use Mav premium for Mandragora as its weak to pyro. Knuckle Duckle you can probably use Clorinde or Neuv. Neuv/Clorinde with Ineffa Coumbina and Kaz. Automation you can Use Skirk Escoffier Furina and Mona. I think with your roster you'll be good for the next year without having to pull to clear fearless. At this point just pull for who you like or pull for meta or even pull cons and sigs to get more mileage out of your current roster. If you want to expand your electro then by all means pull Flins. It would probably make it easier but it probably won't be the difference between clearing fearless or not with your roster. Personally if I had your roster and the extra primo sitting around I'd pull Flins and his sig just for fun. All in all, you have a nice account balance with DPS and supports. 

I actually like Zibai a lot and want to pull her but I was scared of not being able to clear without flins since lunar shilling is really bad + I prioritize meta a bit more than casual players. I’m also not really a skilled player so I can’t do those insane mavuika combos either, these comments encouraged me to pull Zibai!

6.4 is luna 5 which is next patch. I don't know what SO looks like next patch.