I swapped almost all filenames with the title of the upcoming file

Hello, many years ago I somehow managed to switch all track titles within a folder with the upcoming file. As you can see in the picture e.g. the filename of the first file is composed of the title of the second file. The titles of the files are correct, so for example the second file is actually “Rainbow” but has the wrong file name.

Also there are some files without a title at all (calcanda - impact.mp3") so for me it looks like that these are the files that were the “border”, because the switch of filename - title starts then again.

I have really no clue what I did back then. Does somebody know how I can change it back?

MP3tag does not compare data of different files.
So you would have to judge for yourself what the data in TITLE should be.
You cut the effort a bit like this:
Select all the files that have the data from the previous file. (here starting with "Elemental" in the file name, down to "Apache")
Use Edit>(Tag) Cut
Now select just as many files as the number from which you cut the tags but start 1 file earlier (here the one with "Rainbow" in the filename down to "Pinball")
Use Edit>(Tag) Paste.
Now the tag data should appear in the correct files.