No other APIs provide this information, so the kludge with list=search
is the only way. If you know the exact title you can get better results by appending &srwhat=nearmatch
to the query (it will always return 1 result though). See the docs and try the sandbox to learn more.
Note that word counts are not stored in database so the API has to go to Lucene/Elasticsearch for this information which is not exactly fast, so if you need this information en masse you should download a dump instead.