You should make an issue request on those projects for a completely ST3 compatible branch. These plugins should be using "sublime.load_resource()" to retrieve contents. If they want the same branch for both ST2 and ST3, they would just need a simple module like this.
def get_resource(package_name, resource, encoding="utf-8"):
packages_path = sublime.packages_path()
content = None
if int(sublime.version()) > 3013:
content = sublime.load_resource("Packages/" + package_name + "/" + resource)
path = os.path.join(packages_path, package_name, resource)
with codecs.open(path, "r", encoding=encoding) as file_obj:
content = file_obj.read()
Anyways, getting away from the new plugin announcement. Though, perhaps the plugin will need to do something similar. Just took a look at the plugin and noticed the use of sublime.load_settings(). This returns a Settings object, not a string, so the plugin will fail when it runs. It would be great of jps could make the settings object iterable so this plugin could just look at the keys of interest rather than checking all of the keys in the default settings file.