"Tha Gàidhlig agam."
Translation:I have Gaelic.
Highland English, as valid a variation as it certainly is, is not even close to being standard. It is full of exactly this kind of Gaelicism, which is precisely what makes it Highland (Or Island) English.
Nowhere that was not directly affected by the Gaeltacht / Gàidhealtachd says "I have the Gaelic" in English, believe me.
I know the literal translation is "I have Gaelic" but in american english that's competely meaningless. Wouldn't it be better to translate it to "I know" or "I speak"? You do the same with most other languages in french "I am twenty" translates to "J'ai vingt ans" which is literally "I have twenty years".
“American English” is as varied as the country itself.
I have neighbours who would say “I have the cancer”, “she had the chill last night”, “he has the rheumatism”, etc., and there are times they’d certainly extend that type of comment to someone speaking another language (“she has the sign language”, “they have the Spanish”, etc).