On a scale of 1 to 10 how good is this flier team. (list opinions)

Swapping out Florina for Tana, Cordelia, or Hinoka would improve your team quite a bit. Your Ryoma should not have Glimmer, Luna is probably your best bet for a quad set. Ryoma's attack is also too low to effectively use Heavy Blade, even with Brazen Atk/Spd active. The Attack+ Seal is probably his best bet. BSanaki and BNinian would also like having Blade tomes, BSanaki in particular. Also, having two Fortifies and two hones will probably be better than 1 of each buff. Getting two Hones is difficult, and Goad will work until you get another Hone, but you should swap it out as soon as possible.
After you make those changes, I'd say you have a high-end flier team. Probably around 8 or higher.

A bladetome over Ninian and Sanaki would be better so you put to use Fortify and Hone. Firesweep on Ryoma sounds better, because with a brave sword he just become a less powerful Elincia

A couple things:
-Brave sword Ryoma is a bad idea imo. The thing that sets him apart from Elincia is his higher speed, but with Brave, his speed becomes equal to Elincia's, but she'll have 3 higher attack (Amiti is just too good). Instead, giving Ryoma firesweep, Wo Dao, or Slaying would be much better.
-Watersweep on Ninian is... odd. I don't see a particular reason for her to use it. Usually you only use sweep skills on units that have the ability to debuff or buff after combat. Using Ninian for a little chip damage here and there on high resistance mages nonetheless (windsweep would be better), is a waste of a turn when she could instead be dancing. It's especially a waste considering the B skill is probably the most important slot for a dancer. There are several other skills that are better for them, such as wings of Mercy, the dancing buff skills, or even chill skills.
-Florina is fine. Although she attempts to do something that other units could do a little better, going along with the meta isn't always fun.
-For Sanaki, putting L&D with Fortress res makes little sense. You're essentially using two skill slots to give her +2 attack and +5 speed in exchange for -5 defense. Min-Maxing is almost always better than trying to balance a units stats, but if you really want to keep her Res intact, fury is much much better. Then put speed +3 or attack +3 in the seal and you're set. I'd suggest taking off either def/res link or fortify fliers for her. Using them both together on one unit seems redundant, while with hone fliers it means she could buff all stats of a flying ally by 6. Just going with desperation would probably be better for her anyway.
-I'd actually suggest taking off fortify and Hone as a whole. Unless you decide to put Blade on Sanaki or Ninian, taking goad and Ward is better just because of how much more free you can be with your placement, as well as the higher buffs higher buffs you can achieve when stacking them.

Overall it's a decent team, but in it's current state, it's a little underwhelming. I'd probably only give it a 6, but if it got some work, it could be much better.