in the interests list, all letters are shift to lowercase, which is quite useful for merging different spellings. As far as i see, it's only done for the US-ASCII character set, which causes problems for interests using further Unicode characters. For example, the interests Что-Где-Когда and что-где-когда are considered different (that is Russian).
The Unicode standard should provide methods for converting upper/lower case characters. So is it possible to implement that and to convert all Unicode characters in interests to lower case?