First of all. VL's and Tags are 2 different things.
A VL
needs some sort of criteria to subset the Library: Tags is just one of the possibilities.
In most cases, The publisher bloats the Tag list by including every possible permutation of a books topic. I think of Tags as search 'Keywords" not the old (paper) card catalog, where you needed a card for each
possible lookup.
IMHO the Authors name does not belong in 'Tags" There is a DublinCore place for that. Same goes for ANT standard (and most times,REQUIRED) metadata
OTOH they need to tag Series there because there is no STANDARD for series. Because Calibre does deal with Series, you should move that (and/or move it from the title) to The {series} field
Tags are entered into the Metadata of a Book (use the Metadata editor or MDE download). That also auto-populates the Tag browser list and that list becomes
suggestions when entering other tags.
(you just killed all the books tags
when you deleted those)
Moderator Notice
Moved to Library Management