The Chinese & Korean versions & their localization are actually handled by companies located in said countries that are licensing FF14 from Square Enix; the FF14 dev team has little, if any interaction with them, so its easy to make language versions for them when you're not the one doing it.
As for the topic, its simply a matter of perceived demand vs costs incurred. FF14 has effectively 5 entire RPG's worth of text at the absolute minimum when you count up everything across every expansion. In order to translate it all, they'd need to hire entire teams of expert translators and have them working for months for each individual language they'd want it translated to. Coupled with the fact that even with everything translated, they'd then have to hire a team of translators for each and every subsequent content drop or line of dialogue added to the game, means they're incurring a large upfront cost and a continued maintenance cost afterward. For them to deem it an investment, the demand for that language would have to be immense.
Then there's also alternate language literacy in countries where the game is being sold - many EU countries already have one of the game's languages taught in schools, so why bother with a translation when one of the language options in-game covers a good demographic of people from a country they might want to target? Like, Spanish people in the USA would not even remotely factor into their equations and target demographics, since English is the expected standard language of the nation and is known by about 80% of residents. So if they'd look into translating to Spanish, they'd be looking into demographics like South America & Spain, and the Spanish speakers in the USA would effectively be an irrelevant statistic.
Then there's also points like ACE mentioned, where the culture of a country might be more desired towards free-to-play models and microtransactions rather than subscription service games, making FF14 a bad fit and nullifying that country from their equations of profits vs costs.
If Square hasn't bothered with a Portuguese or Spanish translation by now, then it's likely they don't view it as profitable. Whether they're correct or not, its the decision they arrived at likely through tons of analytics and statistics.