As a native speaker, I have never heard this expression. But maybe it is regional? British maybe.

C. truths

I agree, as a native speaker who lives in America I have never heard this phrase "home truths" until now

Hi I'm from the UK and the saying a few home truths is very common. There's no explanation as to why you say truths and not facts because it's just a saying/idiom. 👍

It's 'truths' but I only know that because I taught English in Korea for 5 years. I have never seen or heard this expression used in America.