Necro-bumping this for a quick update.
I finally had some time to work on this today (as well as replacing the batteries on my three Dreamcasts with battery holders, yay!). I replaced the capacitor in C211 with this one to spec from Digikey. Good news and bad news:
The bad news first - still no color. When I power on the system, however I see a flicker of colored artifacts/lines on the side of the screen. I don't know if that's signal noise or an indicator of the issue. Everything else works great though - loads games fine, sound is great, and the composite mod Osgeld used is fantastic, as the picture is clear and there is no ghosting I've seen with other composite mods.
The good news, is that I ruled out C211 as the culprit. And as I'm a beginner at soldering, I'm kinda proud I was able to swap them out and not cause any other issue. That I didn't introduce another problem is a win in my book lol.