I'm not sure about unsportsmanlike conduct reports, but I can speak to verbal abuse.
When you submit a report for verbal abuse, the automatic system will scan the chat log for keywords and phrases that are frequently reported/toxic. If the toxic keywords/phrases are there, the report is considered valid. If the person didn't say anything offensive at all, the report is considered invalid and your "report validity score" is decreased.
Once your score is low, your reports will no longer send any chatlogs to Riot by themselves- instead, someone else on your team will need to report them for the log to be sent. The system will still note whether your report was valid or invalid when someone else's report sent the log, so you can increase your score by only reporting correctly.
So: report -> scan for keywords -> mark reports as valid / invalid -> valid report marked on the person you reported's record -> reported person punished if necessary