The title.
-hp is ok for raven build purposes. Sophia's only slight problem is her color which is not the best in Reinhardt dominated metagame. Although if you have heroes that can cover her weakness then she'll be a good addition. If I remember correctly, a +atk Sophia can one-shot Blyn, so that's useful.
I made a rough calculation and a +atk Sophia can one-shot Bike, so she can potentially be a good Ike solution. Giving her an atk buff or axebreaker will let you deal with him more easily, but she can deal just enough dmg without those additions (based on the calculations Sophia deals 45 dmg with one hit and Bike has 43 hp).
Reinhardt is only one character. And while he's the best in the game, that doesn't mean other colours can't work. Not to mention, you're more than likely to have a counter to him as it is. Reds counter at least four common enemy types in the likes of Hector, Nino, Cecilia and Julia.
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