I think that its worth introducing some internal variable, like mkgmap:stop_words where you can specify your custom wordlist instead of hard-coding it.
In my example from the first post there is no problem with the "street" word because it is not included in OSM street names in Poland - main difficulty with searching is because street can have two different, yet totally valid names:
Miroslawa Dutka - name and surname of a person
Dutka - just surname
of course in OSM we enter full name and surname, but 99% of people use just surname for specifying an address.
Indexing every word in street name would solve this problem :).
best regards
Michal Rogala