Henning's suggestion for abbreviations should work fine for that issue. I could simply use the shorthand in the "series" and "journal" fields and set up the appropriate \abbreviation calls in the document or environment.
As for the larger issue of bibliographies, I've started working on publ-imp-sbl.lua and publ-imp-sbl.mkvi files. I knew I would need this for my own project soon, and I felt it would be useful to myself and the ConTeXt community if I could at least get a rudimentary version working. I'm presently using the reference for examples from the
SBL Handbook of Style, 2nd edition, available at
https://github.com/dcpurton/biblatex-sbl/blob/master/test/biblatex-sbl-examples.ref.txt.
Like you say, some parts are tricky. SBL uses "entry"-style citations by default and doesn't seem to make use of other common alternatives (such as "authoryear"). I can think of some existing alternatives that might get used in specific cases (e.g., "author", "title"), but the recommended shorthand has the form "shortauthor, shorttitle" (i.e., the last name(s) of the author(s) only, followed by a comma and a shortened form of the title as specified in the "shorttitle" field). I could make this the sbl style's implementation of the "short" alternative, since the LaTeX-style bracketed number references are foreign to SBL style anyway, but if would be preferable just to introduce another alternative (something like "authortitle"), then I could also try to do that.
For my immediate purposes, I won't need much more than the @book, @article, @inbook, and @incollection entries, so my focus will be on getting those right, but if anyone is interested in helping, I'll gladly take help. (But it would probably be better to discuss the details in a separate e-mail thread.)
Joey