AACR2 and RDA both constitute application profiles using the same database structure known as MARC. MARC defines the fields and the expected values within those fields (type control) while AACR2 and RDA compose definitions of cognitive models and data fingerprinting (not the LIS terms for these concepts). By cognitive model I mean the mental representation of entities and their relationships and by fingerprinting of data I mean that some artifacts are "well described" when various fields are employed. E.g., a book description needs a publisher, while a manuscript does not.
AACR2 and RDA both constitute application profiles to which the documentation is only provided on a subscription basis. This is a pay-to-play game. This sort of game is not well received by the language documentation community. These facts do no mean that preservation organizations need to avoid MARC, rather a MARC profile could be established and documented in the open.
When considering the future of OLAC and language resource archiving an outstanding question emerges, is this sort of profile something that is of interest within the community?