Clarification would be wonderful.
Thanks.
The general rule is, if it is just an esp file it is fine. No assets were uploaded and no permission is required. Linking to the required files keeps things on the up and up, nothing is stolen that way. You must download the required files for the mod to function as designed.
It is a simplistic approach, but it is most effective and is used extensively for translations to localized versions of the games.
Buddah