FAQ - Problems with ID3v2 tags in Unicode format

I read the pinned FAQ "Problems with ID3v2 tags in Unicode format..." and it worked for me.
Thanks for posting the solution.

I made the changes to the Tag Menu as suggested in the FAQ and the problematic MP3 tracks were now recognizable by WMP 10.0 and tag information once again became visible to WinXP Pro SP3 Windows Explorer. And more importantly, WMP could now play them!

So then as an experiment I changed the TAG menu back to IDv2.3 UTF-16 from IDv2.3 ISO-8859-1 and of course the tracks failed to play in WMP 10.0 and all tag info disappeared from WinXP Pro SP3 Windows Explorer.

1.I'm just curious, why is it that these tracks can't adapt to the changes between UTF-16 and ISO-8859-1?

2.What is the consequence of leaving these tracks in ISO-8859-1 and not upgrading/updating them to UTF-16?

3.Is there a way to modify these tracks so that they can be updated to use UTF-16?