In the current draft of the Special Page
the Wikidata input field has no auto-completion feature.
Based on my experience from
I have the feeling that it should be rather easy to enable autocompletion for Wikidata entries.
Update: This has been implemented and deployed. However, the current approach
does not work and shows the following error:
Skipped unresolvable module ext.math.wikibase.scripts Unknown module: jquery.wikibase.entityselector