I call them useless because this language is a subset of old language that no one uses - or more precise no one should use it any more. It is a regional language from era where every region had their own culture and was occupied by multiple countries so the language is a mix of multiple molded languages that differs by region.

Why it's useless (in example of "Silesian"):

• you can't use it inside the country as it's not official language that you can use when conversing inside goverment (yes, in some local regional governmental offices they understand it, but it's not official)
• in Poland people use the language "Sląski" (or like google call it "Silesian") for many different set's of words and dialects, and they differ to a point that one "Silesian" speaking guy sometimes have issues talking to another "Silesian" speaking guy
• the translation is not helpful to people using that language as they know the official country language too
• the translation probably will never be useful to any other person as they can always going to prefer to use official country language (or English)
• the translation is bad on it's own (as it's only one variant of dozens if not more)

So I'm going to call that language "useless" as other than historical value it should disappear as it this "language" was never fully defined/described and will never due to many "variants".

I don't have an issue that they craeted it, I have an issue that they mixed the this language with other official (useful because still used) languages.

I hope that in the future they will finally cleanup the bullshit language selector in google translate grouping them somehow to make it easier to quickly select the actually useful languages that people actually use on day-to-day basic.

better than siting with dictionary for historian? maybe for me as a "native person speaking (one of the variants of) that language"? no, as I already pointed out it's only one random variant from dozens if not more.