No doubt a player would feel more comfortable on a team with players who speak the same language. However, in reference to the OP and the Marlins, they do try and attract players that represent the community in order to attract fans in the seats and followers of the Team. As I pointed out, that is based on nationality, not language.
The Marlins will go after talent first, fan base type players second, Cuban, Venezuelans etc. Just because a player speaks Spanish is not something they would target based on their historical actions and what I know of the area/fanbase/team.
If the Marlins want Kirk, it will be because of his talent, but not going to get 10,000 extra Cubans at the game because he speaks Spanish. The Chapman’s when in his prime, Guirielle brothers etc, yes.
Speaking Spanish would be helpful with the local media and locals, but unless player is representative of a local demographic, not going to put extra seats in the stands apart from being a good baseball player.