I've done a bit of thinking about this and if you had a list of tags in a spreadsheet, or a comma separated value file, properly formatted, it could be imported easily.
You would have to put the tag group first, then the name of the tag, followed by the optional order. (That I suggested in another thread.)
Animal,pig,3
Animal,cow,1
Animal,donkey,2
Element,zinc,30
Element,gold,79
Element,silver,47
Element,boron,5
Element,hydrogen,1
Potentially, tags belonging to several groups could be input like this very quickly and put into the correct group
Name Order
cow 1
donkey 2
pig 3
Tag Domain Element
Name Order
hydrogen 1
boron 5
zinc 30
silver 47
gold,79