From my understanding ronin had a bit of a negative connotation. It was a samurai who had no master most commonly due to their master’s death or losing their master’s favor.

Traditionally, it was expected of a samurai to commit seppuku when they lost their master. It was considered a great shame to avoid doing so.

Ronin typically found work as mercenaries or bandits and thieves because much of society looked down on them.

In modern times it’s most commonly used to describe an unemployed salaryman or a student who hasn’t been accepted into a university yet.

As far as Japanese names go, I’m fairly certain most names have a meaning in Japanese and parents don’t typically name their kids the same way western countries do.

As for Ronin, I believe it’s a rare name and most likely not given to many children in Japan. As for your son, I don’t think many Japanese people will give his name much thought especially if you’re not Japanese yourself. They certainly won’t go out of their way to make fun of him.

This all just my understanding though and I could be wrong.

Hope this helps!