To give access to new academic skill (Lore, Linguistics, Cipher), you should to make following steps:

1. Give access to the source of the skill. It can be library, a textbook, manual, teacher, a native speaker, and so on. It require some specific actions, any sources you have access by your common training are placed to your advance scheme.
2. Put an effort to learn new skill. It means rolling Int or Literacy (for Linguistics), and you will should to pay time and attention – weeks or monthes.
3. If your roll is successful, you can take listed advance with such guideline for exp: Common Lore cost is 200, Scholastic Lore cost is 300, Forbidden Lore cost is 500, Cipher cost is 200 (but it can be very difficult to find a teacher!), Linguistics cost 100 for Gothic dialect (ship, hive or tribal), 200 for professional argo, 300 for any other human language (such as techno-lingua), and 500 for xeno language.

I think your XP costs are too high. Generally speaking, you shouldn't increase XP costs by more than 50-100 above what a specialist pays. Otherwise you end up seriously discouraging your players from buying the Skill.

I have some slightly expanded houserules on acquiring and developing Skills somewhere, if you're interested.

In my opinion, information is rare and precious resource. So to get access to a FORBIDDEN lore, such as kind of chiphers, sublinks and a lot of "INFORMATION REDACTED" is not enough, you should to understand it too. And it can be difficult without proper mind conditioning.

Scholastic lore is simpler, but it's a kind of education here, on Earth, after all.

And for common lore I increase XP for 100 XP.