Re: point 2, this is because the template data only goes up to 9 authors, unfortunately.

To fix this you have to manually add additional authors to the template data definition which is theoretically infinite.

Re: point 1, I tweeted asking for an example and got it ... I can see now they were in the thread, but the thread you linked to here doesn't show me your replies at all in the new Twitter UI -_-!

I've added two more author slots to the TD here: https://en.wikipedia.org/w/index.php?title=Template:Cite_journal/doc&type=revision&diff=917358513&oldid=914737150&diffmode=source

But you can theoretically go on quite a bit longer than that.

This may be a sub-task of T54582.