Sometimes we see weird results in the prefix search because Cirrus uses different matching rules then the jquery.suggestions library. In English, for example, Cirrus flattens high ascii. Searching for "resume" will return "résumé". Cirrus is quite capable of highlighting the result properly, but it has no way to tell the front-end what the result should look like.
I don't believe it would be practical to replicate Cirrus's logic on the front end because it can change and it is different for different wikis.