Help me find the right string to edit this Tag

Hello everyone.

  1. I have a Tag "Year" displayed on Mp3Tag is "1981\\1981-01-01"
    (It show 2*\ but I dont know why forum's editor only show 1*\ then I typed 3*\ to display 2*)

And on my Foobar2000 it is displayed is "1981;1981-01-01"
I want to ask, how I make it become to "1981-01-01"
I tried these strings but it is not work.
$Left(%year%,6) - result 1981
$Left(%year%,5) - result 1981
$Right(%year%,10) - result 1981
$replace(%year%,$left(%year%,5),) - result blank
$replace(%year%,%year%,$right(%year%,10)) - result 1981

  1. And ... Any Tag field include ","
    Example
    I want to change tag "Artist 1, Artist 2"
    to
    "Artist 1; Artist 2"
    I tried many times but can not find the right string.

Please help me. Thank you for reading!

Indicates a multi-value field. You can check that in the extended tags dialogue Alt-T where you should find at least 2 fields of the type YEAR.
YEAR is, according to the ID3 standard, a 4-digit field. So the long version would be at least problematic.
A field for a more detailed date would be RELEASETIME.
If you want to keep both data parts but assign them to the correct fields, I would suggest an action of the type "Guess value"
Source: $meta_sep(year,==)
Target format string: %year%==%releasetime%
This should put 1981 into YEAR and 1981-01-01 into RELEASETIME.

Make sure to have a backup if anything goes wrong. Try it on a single file first.

It is not quite clear to me what you want to achieve ... replace the comma with a semicolon in the field ARTIST?
That could be achieved with a an action of the type simple "Replace".

Please note that there are a number of artists around that have a comma in the name.
E.g.
Earth, Wind & Fire
Dave Dee, Dozy, Beaky, Mick & Titch
Bell, Book % Candle.
I am not sure if these names would benefit from the replacement.

Hi Ohrenkino,
Thank for your suggestions. I will try something. ^^
Good day, mate!