I don't see a bug here.
Those players got in the game when they did because that's when the starters were tired enough. You also had the Let Them Play, which makes the coach completely disregard fouls when making subs, a setting which makes the coach substitute less often.
You had one player backup two positions. Playing just 2 minutes at one of them is not abnormal at all.
So all in all, it looks pretty fine to me.
Thanks for your opinion which I dont share...
I have tried one player to backup two positions several times and this result is abnormal. See my previous match in PL for instance - and those two starters have worse stamina.
And you tell me that player with stamina 4 (starter SF) was tired after 36 minutes of the match? I think that it is normal to substitute after 8 minutes.