Can jpm create a plugin for for Firefox 37.0 or older?

Question

Jpm creates install.rdf with compatible versions range starting with 38. If created addon which works on 38, is forcefully installed on Firefox 37.0 it fails (there are no obvious related errors in the browser console, plugin installation just has no effect except for addon entry on about:addons).

1. Can I still use jpm to create addons for older Firefox versions?
2. Is cfx indeed deprecated if its replacement can't create an addon even for beta channel of updates?
3. Should I continue to look for a bug in my addon which worked fine on 38 and on 37 (being built with cfx)?

Answer 1

1. no, unless you use an older version ( v.0.0.23 or below I think )
2. deprecation means we won't fix any bugs and are encouraging people to check out jpm - not that you cannot use it. Until Firefox 38 is released it is completely reasonable to use cfx to package extensions intended to be used by Firefox users.
3. I have no idea - you haven't really provided enough information about the bug.