This is still a problem I had it triggering multiple times on wrong mana values.

This is still a problem. Talion's effect still triggers on cost reduced cards when it shouldn't.

Still bugged, it seems. My opponent had it at 3, I cast a Rootrider Farm (cost 2) and it triggered. Logs attached.

Same happened twice in different games, he chose 3 (even though he saw my hand and knew I had 2 cards with CMC 4 and 1 card CMC 6). Then I draw a Liliana CMC 3 and chose not to cast it to avoid the trigger, casting the CMC 4 card. Even that he was showing to have chosen 3 he still triggers.

It's the last game in the log.

Triggers on mana value 4, eventough the opponent choose 3

I had Talion trigger on every spell I cast no matter what spell I cast.

And how many creature cards were in your graveyard? Old Stickfingers has a characteristic defining ability that defines p/t, which works in every zone, and Tallion also triggers when either of those matches the chosen number.