I thought you were talking about the [Name] field/tag initially. But I see that it is the file name you are concerned about. I guess that makes sense, because MC doesn't write tags to video files, only into the Sidecar file, which Serviio and Plex aren't going to be able to read.
MC names movie recording files the way it does because movies may be broadcast more than once, and so more than one recording may be made of it. Basically, the recording date, and suffixes if required, make the filename unique. But that doesn't mean that you can't change the file name automatically.
Okay, first, your EPG must have the [Year] metadata, and then MC will include that in the [Year] field in its Library. Then all you need do is tell MC to tag the new recording using the [filename (name)] tag, which will rename the file.
If the recording is made with a subscription, you can just add the tagging rule to the specific Recording Rules, in the "Apply these tags (optional)" section of the rule. It is similar to the "tag on import" functionality described here:
https://wiki.jriver.com/index.php/Tag_on_ImportBut that won't work if the recording is a "One time recording...", because you typically won't edit that rule. You would have just clicked the "record" button on your remote, or similar. But MC has you covered. Go to "Options > Television > Recording > Recording default - Tags to apply when recording is done" and set up a rule for the [Filename (name)] field there. Something like;
If([Media Sub Type]=movie,If(isempty([Year]), [Filename (name)],[Name] /([Year]/)),[Filename (name)])
See the attached image.
Basically what it says is "If the recording is a movie, and the year field isn't empty, rename the file to 'Name (Year)', otherwise leave the file name as it is".
Buy the way, I think MC will rename the file and leave the file extension as it, but I haven't tested that using this method.
Leaving the name alone if the [Year] field is empty seems like the best idea. You will need to rename those files manually using the Rename, Move & Copy Files function, after populating the [Year] tags using the "Get Movie & TV Info..." function on the file.
You should test carefully to see if that works for you. Adding global tags to all recordings must be done carefully. Plus of course, if the [Name] tag isn't properly determined from the EPG metadata, then you will get the wrong file name anyway.