Atleast the subtitle issue I've figured out for now, MCEBuddy looks like for a title match and subtitle match to get the information. However if also checks for a air date match if it doesn't find a subtitle match. if it find an air date match
it assumes the subtitle in the wtv file is incorrect (which is the case in MOST cases) nad then updates it. Heretv.com has the wrong data and hence it ends up giving your wrong data.
This is a typical chicken and egg situation where users have complained that either the wtv data is wrong of the website data is wrong. Hence the solution was the do a match and then if air dates match use the website data.
The reason is that wtv data cannot be corrected, website data can be. I would suggest just gototv.com and submit an update for the series air date (i.e. correct the air date for the wrong series being downloaded) and it'll solve your problem (as well as help the community :)