I dislike the original Space 1889 language rules for two reasons. First, as is the case in a number of roleplaying systems, they make it harder to learn new languages the more languages a character already knows, the reverse of how it actually works. Secondly, it seems artificially restrictive in the way it limits the number of languages known, and the levels to which they are known.
So, instead of the standard rules, I use this alternative version. A character with Linguistics skill, instead of having one language at the skill level and (skill level - 1) languages at half the skill level, gets a number of levels equal to that they would get with the standard rules to divide among any languages as they see fit. For the different levels of Linguistics skill this gives the following numbers of levels:
Secondly, I have removed the Linguistics skill from being associated with Charisma and made it a thing on its own. This means that the number of languages a character can learn in play is limited only by their chance to learn them, and not by their stats. Because of this, rather than making characters pay experience points to advance their Linguistics skill level, I instead make them pay to advance their knowledge of individual languages at the normal rate (i.e. a number of points equal to the desired level). This makes it easy to improve languages with which a character is unfamiliar, but harder to improve languages in which they are already fluent.
As an aside, this is a link to the Ethnologue Database which covers just about every language on Earth.