Dear Peter, I've tried various things, but this is all new for me and I can't seem to get it working... Perhaps you see something obvious that I'm overlooking?
This is the code now that I'm trying...
{% set term = mb.get_the_terms(post.ID, 'writer') %}
{% set postauthor = mb.rwmb_meta( writer_first_name, '', term.ID ) %}
<p>
Author: {{ postauthor }}
</p>