In reference to this issue:
According to Simon (by separate mail):
"The behavior Zotero uses (which no one has complained about so far, as
far as I know) is to add a comma between the author name and "et al.“
only when et-al-use-first is greater than 1. If we want to make things
simpler than that, I would argue that the default should be not to
include the comma.”
If current behavior is a winning combination, it might be worth
preserving it in the processor and the specification.
One way to do this in the processor would be to substitute the
inter-name delimiter set on cs:name for the et-al prefix (whether
implicit or explicit), whenever et-al-use-first > 1.
While a little more flexible than the current behavior, this would
still be assuming latin/cyrillic punctuation conventions, and may
produce unwanted results with other scripts. But many other similar
issues will crop up when we start digging into the Asian languages,
and kicking this one down the road a bit won’t add significantly to
the burden of sorting them out.
If there are no strong views, I’ll go ahead and implement the
substitution approach, to keep the processor in line with current
Zotero behavior. Otherwise, I’ll follow whatever concensus emerges