In the about section of the old site (About » Extensions) it is written the extensions migrated away. So I follow the instructions and logged in in the new site.
The problem is that my extension (Venetan Spellchecker (Dictionary, Thesaurus, and Hyphenation) » Extensions) was not there.
Following the instructions here https://extensions.libreoffice.org/en/using-this-site-as-an-extension-maintainer/ I tried to claim maintainership writing to hostmaster@documentfoundation.org but no one answered (hoping that will result in my extension been ported).
How can I have my extension migrated in the new system? Should I re-insert every release I did so far?