Re: I can´t find the nabble email address to suscribe it to a googlegroup
The application type change shouldn't affect the mailing list archive. But in any case, please create a new archive for the mailing list. After that, you will be able to move the messages from the old to the new archive. Here is how to merge them:
(1) Open the old forum and click on "Options > Structure > Change parent", select "Set a New Parent" and paste the link to the new forum (After this step, the old forum should be a sub-forum of the new forum)
(2) open the old forum and click again on "Options > Structure > Change parent", then select "Merge into Current Parent". This option will move all topics to the new forum.
PS.: The "Delete" option that you don't see is actually a bug that will be fixed by the next release.
Re: I can´t find the nabble email address to suscribe it to a googlegroup
That's true. You changed the mailing list settings before and selected the option "Hide Mailing List From Users". I fixed this, but I will also fix the Options menu because it should have displayed the "Mailing list settings" for you. So you don't have to create a new archive, just re-subscribe the old one.