I would try highlighting the words and try:

FIND ", " (that is, a typed comma and a typed space)
REPLACE "], [" (that is, close bracket, comma, space, open bracket]

You would still have to open bracket your first word and close bracket your last one, but if there a bunch of comma-separated words in a string, that would do most of it rather simply.

If you are interested in a VBA solution, this thread may guide you there, as it's asking something similar, only with quotation marks. https://www.msofficeforums.com/word-...dd-single.html