No doubt some may be wrong, but with around 40 subtitles per episode, it's impossible to check and compare which are wrong and which are correct. But from my investigation, I feel some episodes were released by different groups, so depending on the group, the start of some episodes were and did used to be different. Depending on the fact if they are showing a recap scene from the previous episodes or not, etc.
Example, the following two subtitles are definitely for the same episode, but if you click and check under "show preview", the text starts differently for both files.
Sub 1: https://www.opensubtitles.org/en/subtit ... members-en
Sub 2: https://www.opensubtitles.org/en/subtit ... members-en
Maybe that's what you are experiencing, but we wouldn't be able to help you get the right sub for your release via Firestick. Your option would be to go through the entire list, one subtitle would eventually fit your specific timing and set. I'm guessing manually using the site wouldn't be an option.