I dunno much about Unicode, but I imagine it is a regular language? (Aka: acception / rejection can be determined by regular expressions / finite state machines)
If so, regular languages are one of those 'surprising things that can be parallelized'. It doesn't seem possible at first thought though.
Just in case, here "Unicode routines" refer to Unicode encoding routines, not other more complex things like normalization. They are pretty regular but their automata would be relatively simple. (By the way, SIMD-accelerated regular expression parsing is indeed a thing [1], if anyone wondered.)
[1] https://www.microsoft.com/en-us/research/wp-content/uploads/...
Intel has an implementation of this technique here as well: