We currently don't support displaying multiple users' typing statuses in a PM narrow.
In a huddle/group PM, we only handle typing events from the first email in the narrow specification.
We should be handling typing statuses from all the senders in the huddle.

The web-app handles multiple users typing this way:

Person 1 is typing...
Person 2 is typing...

with Person 1 being the user that sent the most recent start update. Since we're limited on footer area, we would want it shown in the same line, i.e., Person 1, Person 2 are typing... for the first few users, and on crossing a threshold, resort to displaying Multiple people are typing....

Each user's typing status in the huddle should be displayed accurately in the footer, without overlap/change in the handling of the typing status received from the other users, i.e., a stop event from Person 1 in the above scenario should not affect the display of Person 2's typing status.

This can be further discussed here, or at #zulip-terminal > Multiple users typing.