Code:
string.gsub("Echo of a Pandaren Monk", "(%S[\128-191]*)%S+%s", "%1. ")
That pattern doesn't require one or more non-whitespace
characters. It requires one or more non-whitespace
bytes (eg. \32 is flagged as "whitespace"). In the case of multi-byte characters, the extra bytes per character are matched. In the case of \208\176, neither \208 nor \176 by themselves are "whitespace" so string.gsub sees them as separate non-whitespace entities, since it is not Unicode-aware.
As for your other question, "Echo of a Pandaren Monk" [url="http://ru.wowhead.com/npc=58669"]in Russian[/b] is "Эхо пандарена-монаха". The preposition "of" is generally not used directly in Russian (the declension of the relevant noun changes instead) and articles like "a" and "the" are generally omitted. There are one-character words in Russian that are used often -- в, с, к, у are several that spring to mind -- but I don't know if any of them appear in NPC names.
Edit: A quick scan of Wowhead in Russian finds at least one NPC name with a single-character word --
Эрунак Говорящий с Камнем. There are likely more, but I quit looking after spotting the first one on page 2.
