use AppleScript version "2.8"
use framework "Foundation"
use framework "NaturalLanguage"
use scripting additions

–The result is on macOS 13.6.5 / 14.4 / 15.2
set aRes to testNLLanguage("NLLanguageEnglish") of me –> true–> true –true
set aRes to testNLLanguage("NLLanguageFrench") of me –> true–>false (macOS 14)—> true
set aRes to testNLLanguage("NLLanguageGerman") of me –> true–>false (macOS 14)–> true
set aRes to testNLLanguage("NLLanguageItalian") of me –> true–>false (macOS 14)–> true
set aRes to testNLLanguage("NLLanguagePortuguese") of me –> true–>false (macOS 14)–> true
set aRes to testNLLanguage("NLLanguageSimplifiedChinese") of me –> true–>false (macOS 14)–> true
set aRes to testNLLanguage("NLLanguageSpanish") of me –> true–>false (macOS 14)–> true

set aRes to testNLLanguage("NLLanguageUndetermined") of me –> true –>Natural Language framework doesn’t recognize(macOS 14).–> true
–macOS 14.7.2で再確認したところtrueに

set aRes to testNLLanguage("NLLanguageAmharic") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageArabic") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageArmenian") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageBengali") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageBulgarian") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageBurmese") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageCatalan") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageCherokee") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageCroatian") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageCzech") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageDanish") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageDutch") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageFinnish") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageGeorgian") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageGreek") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageGujarati") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageHebrew") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageHindi") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageHungarian") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageIcelandic") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageIndonesian") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageJapanese") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageKannada") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageKazakh") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageKhmer") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageKorean") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageLao") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageMalay") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageMalayalam") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageMarathi") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageMongolian") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageNorwegian") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageOriya") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguagePersian") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguagePolish") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguagePunjabi") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageRomanian") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageRussian") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageSinhalese") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageSlovak") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageSwedish") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageTamil") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageTelugu") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageThai") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageTibetan") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageTraditionalChinese") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageTurkish") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageUkrainian") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageUrdu") of me –> false–> false–> false
set aRes to testNLLanguage("NLLanguageVietnamese") of me –> false–> false–> false

on testNLLanguage(aLangName)
　　set aText to "use AppleScript
use framework ＼"Foundation＼"
use framework ＼"NaturalLanguage＼"

　　set targLang to (current application’s " & aLangName & ")
　　set aEmb to current application’s NLEmbedding’s wordEmbeddingForLanguage:(targLang)
　　if aEmb = missing value then return false
　　return true
　　"
　　return run script aText
end testNLLanguage