that's why you can't clear horus.... you have WIND... they're weak against fire, meaning you'll take more damage and deal less.
clearing with a disadvantage is only for the overpowered... you're better off using another team for that, even if you're using SR/R characters. in fact, even a mix of off-element characters is better than taking on fire with a wind team.... it's just suicidal
and yeah, that eidolon is good for new players due to the HP boost, which you likely need. the better one is a long ways away anyway (Meng Huo, who did up to a 40% HP increase and can reach over 2k in atk).
you'll quickly drop Sakura x Mio for others though so make sure you got enough copies to get her to lv100 so you can get more use out of her.... you still need at least 6 events before you can start picking which eidolons to use for stats and possibly main effect, less if you got lucky/rerolled on the gacha