2.2.14 [RFC5545] Section 3.2.10 Language

V0021:

The specification describes the optional LANGUAGE parameter.

Microsoft Exchange Server 2007, Microsoft Exchange Server 2010, Microsoft Exchange Server 2013, Microsoft Exchange Server 2016, Microsoft Exchange Server 2019

Microsoft Exchange Server only exports a LANGUAGE parameter for the following properties:

On import, Microsoft Exchange uses the value of the last LANGUAGE parameter found in a SUMMARY, LOCATION, COMMENT, or DESCRIPTION property within a VEVENT component. All other instances of the LANGUAGE parameter are ignored.