"Language Type" seems to apply only to audio books as far as I can tell yet it appears to be on every edit page for books.
The new format is almost unbelievably clunky and useless for the majority of books.
It is full of mostly irrelevant options such as :
Does this product have customisations?
Target Audience
Part Number
Maximum Reading Age
Included Components
Lexile Code
GDPR Risk
Number of Pages Unit
Dangerous Goods Regulations
EU TSD Non Age Specific Warning
Compliance Media Source Location
GPSR Safety Attestation
Product Warranty
GHS Statement
...yet there is no field for important attributes such as editor, illustrator, preface, foreword etc &c
In any case, these fields should only be completed by the publisher/manufacturer. They are for the most part completely irrelevant for resellers (almost certainly amounting to at least 99% of the sellers who are forced to scroll through this nonsense).