RaiseWikibase requires direct write access to the wiki’s SQL table, and I am skeptical that kind of access would be opened up. In general, having multiple applications write to the same database (the Wikibase application itself vs. the RaiseWikibase script) can be very hazardous if you do not take precautions.

On my own Wikibase that I self-host I use this extension: <https://www.mediawiki.org/wiki/Extension:BatchIngestion> which exposes an API for batch writes. I admittedly have only done a small test with it but I understand it works way faster than WikibaseIntegrator. I am not sure the Wikibase Cloud team is necessarily inclined to deploy random extensions on demand, but it seems like a much safer option than RaiseWikibase.