Some time ago I suggested some improvements for Importer when dealing with import from IPB 3.4.x ( Importer: some bugs and ideas to improve data import from IPB 3.4.x ).
Most of them are now fixed - thanks 
(I replaced file IPB3xExporter.class.php and run conversion again today), but I spotted two issues. I will create separate threads for them as second one is more complicated.
First issue: quotes are missing author name. In original post in IPB it looks like this
[quote name="some name" post="1107085" timestamp="1457168868"]Content[/quote]In database this is saved as:
<blockquote class="ipsBlockquote" data-author="some name" data-cid="1107085" data-time="1457168868">Content</blockquote>After conversion I got in WBB:
[quote]Content[/quote]Generally I see in database two kind of quote types - with blockquote tag shown above and simple BBCode [quote name="some name"].
It is possible that there was some change in the way of dealing with quotes at some time in IPB and thus two kinds are present in my database.