If usage seems more or less balanced between several different forms and one of the forms is that used on the heading for the people, there's no need to research the people. However, if your research leads you to think that there is a strong preference in the literature for a form of name for the language that is different from the name set up for the people, then you should research the people to see if that form should be changed also. The answer based on my experience as funnel coordinator is that yes we should try to make them the same, but it is not required.
Solid research is necessary to back up a choice of subject heading.
When establishing subjects it seems that English sources are preferred. In your case, no location is needed since you can easily find a language name from the home page. A location statement for an online resource is generally only needed when you have to take another, not immediately obvious, step to get to a point where you can retrieve the search result. For example, in searching Geonet you have to pick a country before you can start searching and in searching Firstsearch you have to pick a database. That is the year LCSH was put on line.