I have rarely faced and never played this line, so take my words with a grain of salt. Although probably not the most active or incisive way to respond to the Ruy Lopez, I think it's fairly solid. I would reckon this opening would only be insufficiently sound if two strong GMs were playing. That being said, at the lower elo range, it is sure to surprise most opponents, which is often enough to get an early advantage, whether it's time, psychology, or tactics. So for most people, I think this opening is a pretty good choice.
However, that your opponent missed 7.d5 and that you then also missed ...d5 yourself.
It would appear that you bettered a far superior online opponent (on paper or maybe on Elo or Glicko rating alone), but you yourself (a bit like me actually) are quite highly rated in tactical puzzle training stuff ...which is a large part of Chess. Your tactical acumen approaching 1900+ level, across above 100+ games already, which then shows that if you do survive the Opening exchanges, you will then have some very good chances.
The Cozio can for sure offer some nice chances here, for playing mid-game tactics. Your opponent in this game has also played 115 tactical training games for a rating of 1730 meanwhile ...so you chose the very best way to beat him (or her) here. A nice win.