A poster posted an error he was having with the Advanced Item search, so I checked it out.
Sure enough, if you search for Spell Crit Rating, the field automatically switches to spell hit rating after you click search.
Moreover, I did a search that should have turned up an Azuresong Mageblade if it actually searched Spell Crit Rating or a Blade of Vaulted Secrets if it searched Spell Hit Rating instead. Nothing popped up.