Language Drift: Sort-of averted for Eldraeic, due in equal parts to its origins as a designed language intended to communicate precisionist-grade thought and to its ongoing tending by the logotects, et. al., of the Conclave of Linguistics and Ontology, who are prescriptivists nonpareil. Only sort of, however, since their department of Worthy Innovations routinely combs the language as it is spoken for, well, worthy innovations to be taken up into the canonical version.
Since they’ve been doing this for a long time, and since almost nothing can ever be thrown out due to the obvious need for backwards compatibility in language design, the result tends to be — well, if it were English, they’d be like this (courtesy of xkcd):
Played rather straighter by most other languages of the Worlds, although both the influence of Eldraeic via Trade and that of the pervasive communication networks of starfaring cultures do tend to slow it down a bit.