Open text file in Numbers when it is space delimited, but some fields are strings in quotes with spaces
if you have an editor that can use regex (for example textwrangler or bbedit)
or you are willing to use sed (in this case remember the -E flag)
or you can write a small filter in any language you know (for example perl or python),
you can first change the brackets into "s and then use the regex:
    s/\ (?=(?:[^"]"[^"]")[^"]$)/\t/g
to convert any space not between quotes into tabs, so that Numbers will import it correctly (it's not that I am this good with regexes, it is explained here: regex101.com/r/sU3fA2/29)