Translation of record types is available via Translation Workbench. My question is:
How can I add RecordType translations to a managed package?
It looks like what you want to do is add the "Language Translation" to your Managed Package. If you have a translation set up for a metadata component that you are deploying, it also be brought into the installing org.
When adding the CustomObjectTranslations files to a package through a deployment using the metadata api, even though the deployment said it was successful and the translations were visible in the developer org, the language translation wasn't actually included in the managed package. To get them included in the upload, I actually had to go into the UI to select the Language Translation and which languages to include.