When there is new article unconnected with Wikidata, I can add interlanglinks to connect it - but only with another language in same family.
Eg. I have new article [[q:cs:Karel Janák]]. There is no other article in another-language wikiquote, but exists [[cs:w:Karel Janák]]. When I want connect articles together via Wikidata, I must go to cs.wiki, then go to Wikidata and there add link to cs.wikiquote:Karel_Janák.