I don't think removing case sensitivity would be a lot of manual work, but it will require a reindex to change the index. I'm not sure why we decided on it being case-sensitive, I'll try to figure it out and if there's no reason we can change it. Note that this will apply for all fields, so if there are properties where case does matter it may get things wrong.
As long as it's possible to get the original case from the API then you can remove false positives in the case sensitive case by doing another call for each result and then comparing equality. Whereas if there are no results than it's very hard to get a result as you have to try every case permutation - all lower, all upper, camel case, sentence case, title case or completely random :). That said, string values are now available from the general search which does work, so maybe there isn't a need? i.e. https://www.wikidata.org/w/api.php?action=query&list=search&srsearch=10.1371/journal.PCBI.1002947 works.