Hello, and welcome back to the game!
From what I’ve seen posted on the forums, the Argent Archives and discord servers, there’s not too much roleplay (guilds, events) focusing on the tauren in specific. Which is a shame!
While not too active either, could try asking in the Tauren Chieftains discord.
Here’s some generally Horde themed guilds that I found:
There might be other guilds who don’t advertise on the Argent Archives or forums, but may post on the Horde AD RP Community discord.
Best wishes getting back into roleplay!