Temporarily switch to an already-packaged format
file data/default.strict.yaml
is stored in a format that seems to be YAML but really isn't: It gets parsed by strictyaml, a library deliberately sidestepping the YAML definition.
Please, if YAML is unsuitable for storing data then pick another common file format.
Seems to me there is really no need to avoid regular YAML here: Just make sure to quote strings if afraid of the Norway problem.
Concrete reason I bring this up is that Debian does not have that special library "strictyaml" packaged, so requiring it will delay further the packaging if this project officially for Debian.