I just did a manual workup of all 3-homer games since 1992, split out by team’s home stadium. Note that this doesn’t take into account stadium changes–for example the numbers for Washington include all 3-HR games by Expos or Nats hit at home, and all 3-HR games by visitors at the Expos’ or Nats’ home stadium.
Team H V Total CHC 9 8 17 COL 8 9 17 TEX 9 7 16 CIN 9 6 15 BOS 6 5 11 TOR 6 5 11 MIL 7 3 10 PHI 2 8 10 CLE 5 3 8 ARI 4 3 7 BAL 3 3 6 DET 3 3 6 KCR 0 6 6 NYY 5 1 6 WSN 2 4 6 ATL 1 4 5 CHW 1 4 5 HOU 2 3 5 LAD 3 2 5 SEA 2 3 5 STL 3 2 5 OAK 3 1 4 SDP 1 3 4 LAA 2 2 4 PIT 1 2 3 SFG 1 2 3 TBR 2 1 3 FLA 1 1 2 MIN 0 2 2 NYM 0 0 0
So these are 3-HR games by home-team players, and by visiting players, and the total.
Check out the disparities for the Brewers, who have hit a lot more at home than their visitors have, and the Phillies, who have yielded a lot more at home than they’ve hit.