As part of template translation (T139332), users may find templates with lots of parameters. Only the most relevant fields should be visible initially.
The main focus for template translation is to adapt those fields with information in the source template. This means to show initially only those fields from the source that contain information, and only the equivalent fields in the target.
The translated template can present other fields in a more compact way to avoid them getting in the way (e.g., behind an "add more properties" action) but allowing the user to add information to them if needed.