I'm not entirely sure H2H matters / takes precedence over rounds. Looking at the current TF2 ruleset implies this text has always been there and was always ignored, or only came into being prior to this season.
I remember the seeding debacle with last season's IM playoffs. Both Mad Luxurious teams and Part Time Fraggers were 10-6, MLB had 47 rounds, MLX had 46, PTF had 45. Blue beat Gold and lost to PTF. Gold and PTF didn't have a regular season matchup. But then playoff seeds ended up as #5: MLX, #6: MLB, #7: PTF for whatever reasons... Can't even look at forfeit rounds or whatnot because Blue had less than Gold / PTF. Weird shit all around so maybe this was a bad example.
Bird Noises and 6cuties in S19 Open were both 15-1, where Bird Noises' loss was to 6c. If H2H came before rounds, then 6c should've been 1st seed but Bird Noises got 1st seed, and they had more rounds.
I dunno lol.