You could do this with the help of Regluar Expressions.
You first need to replace : and \ signs in your taglist file with a text editor with ### because these chars are treated specially by mp3tag.
Then you would import this converted path to a single tag field, e.g. %comment%.
Now with a series of RegEx actions.
This would be the content of a .mta file for this purpose:
[#0]
T=4
F=COMMENT
1=^.{1}###.*?###.*?###.*?###.*?###.*?###(.*)
2=$1
[#1]
T=5
F=ARTIST
1=%comment%
[#2]
T=5
F=ALBUM
1=%comment%
[#3]
T=4
F=COMMENT
1=^.*?###(.*)
2=$1
[#4]
T=5
F=TITLE
1=%comment%
[#5]
T=4
F=COMMENT
1=^(\\\\d{2})\\\\..*
2=$1
[#6]
T=5
F=TRACK
1=%comment%
[#7]
T=4
F=TITLE
1=^\\\\d{2}\\\\.\\\\s(.*)
2=$1
[#8]
T=4
F=ARTIST
1=^(.*?)###.*
2=$1
[#9]
T=4
F=ARTIST
1=^(.*?)\\\\s-\\\\s.*
2=$1
[#10]
T=4
F=ALBUM
1=^(.*?)###.*
2=$1
[#11]
T=4
F=ALBUM
1=^.*?\\\\s-\\\\s(.*)
2=$1
but you now said your paths in the taglist file are inconsistent, so these actions would need some modifications i think