The Better Trims property data files are stored in the following structure:
data/<namespace>/bettertrims/trim_properties/<property_name>.json<property_name_2>.json...<other_namespace>/bettertrims/trim_properties/<property_name>.json<property_name_2>.json...
The name of the property is determined by the filename of the JSON file.
The translation key for the property is inferred from the namespace and property name as follows:
bettertrims.property.<namespace>.<property_name>
This key is what the property's name will be translated to in-game.