Thank you for the links. As the "how to import" question will be important for many users I'd highly suggest to add this information into the docs and wiki.
Did no one (including the "paid support") wrote this importer before?
If not I'd even suggest the "paid support" have at least a thought if an official import option for Allura exports would help nodeBB in general to grow - especially now as SourceForge (which uses Allura and has the same export) looses users which look for alternatives which are able to import the old forum data with as less as possible effort.