If youre using instant feedback as some sort of indicator, just know that those are not meant to tell you a specific player's account status. Their purpose is to occassionally remind players that their reports do get reviewed.
Also, remember there are 2 tiers of punishment that come before a temp ban. You cannot tell if someone got a 10 or 25 game chat restrict.
I can take a pretty good guess at whats happening as far as people not getting banned for gameplay offenses. There are hundreds, maybe thousands, of people like you, who make it their business to police the community and do everything they can to confirm that people are getting punished. They use the client report system, AND then add to the report load with tickets for the SAME fucking thing they reported already. Youre just adding more work for Riot. They already have to comb through thousands of reports daily, and people like you double it. Now its gonna take them longer to get to legitimate reports. They probably have a few thousand false reports before they get to your two reports against the same player for the same game. I imagine it just is gonna take some time because everyone fucking reports for little bullshit mistakes and off meta shit because they think thats trolling.
So if you really wanna help the community, report less frivilously, and dont make two reports for the same damn thing.