OpenAtlas

I would like to know what the difference is between the addition of controlled vocabs from the reference system and import from a Skosmos service.

The import of vocabularies/thesauri from a Skosmos service is for using that vocabulary in our type system. The reference system is a general way to link entities and types to external authority documents, like wikidata, geonames, gettyAAT, GND etc.
If you import a Skosmos vocabulary, the types are also linked with the external reference system to the vocabulary. The Vocabs import presents just an easy and fast way to get a standardized type hierarchy. But you can also make your own type hierarchy and link each type to a vocabulary

1. Since I only imported the English version of iDAI, is it okay to import again for the German version?

It is possible to import the same thesaurus with another language, but I would heavily suggest not to do it. It will lead to data inconsistency and you have duplicated types.
I would suggest choosing the language you are comfortable working with, because OpenAtlas currently doesn't support multilanguage for entities/types. But since the types are linked to the original thesaurus, the information is not lost and can be imported, if OpenAtlas supports multilanguage.

2. If later on I would like to remove the entire vocabs, do I have to delete the custom type one by one (there are 1100 of them)?

If you want to remove the whole type, you can just delete the top type (e.g. iDAI.world thesaurus). It will ask if you really want to delete it and list all subtypes and entities connected to it. But then you can delete everything in one go.

3. can I re-import the same vocabs? will it cause any file conflict?

You cannot re-import the same vocabulary, it will throw an error, but nothing else will happen. You can rename the old one, and then import the new one. Do you have a use case for that?

If a vocabulary service updates their content, you have right now two options:

1. Add the changes manually, so make the new type and link it to the vocabulary. If there are not so many changes, this is quite feasible. You can also change very easy the order of types (if you edit a type, you can change the super type).
2. Rename the old one, import the new one, and then move the entities to the new one. There is a button for that.

We thought about an update scenario, but there will be merge conflicts and so you have to do it manually anyway.

In conclusion, it can be imported from VOCABS, but not updated. I will close this ticket, if new question arise feel free to open new ones.