Why are you trying to switch the search to use HTML entities?
Omeka doesn't usually save the content in the form of entities, unless you manually do so with the HTML inputs. Generally, it's all geared toward using "pure" UTF-8 for characters.
I need to do this in order to search for special characters such as ö. The search only works correctly if I replace ö with ö
Oops, just realized the last character rendered wrong that should be the html escaped version of ö (& + ouml) that works in search, but not ö itself.