Currently our Import process doesn't handle revision deletion at all, even though the relevant data is exported into the XML format.
This has the following effects for revisions:
|Before export||After import|
|Username hidden||The revision is skipped completely|
|Edit summary hidden||Blank edit summary|
|Content hidden||Blank revision (no content)|
To me, the bottom two behaviours seem acceptable. We shouldn't skip revisions for which the username is hidden, though. The suppressed username should be replaced by user ID 0 and a user_text such as "Unknown user".
For log entries, any kind of selective deletion seems to just blow up WikiImporter; see T34876.