Thanks all for joining this topic.
Thank you too 
The word "feathering" does not appear in LibO but
it is in GIMP and other graphics as well.
I know it, because now I don't have time to check translations in LibO (and Launchpad as well). So, I simply checked it in a useful site for Esperanto translations about computing and similar.
The point is, I want to ask you how you translate words that is new
and very "English".
For Vietnamese, we will use the second way to translate.
In Esperanto we use the second way because Esperanto itself doesn't permit to use foreign words without adapting them.
In Italian, however, we use English words even if there is an Italian version 
So, I think every language (and so every language team) should choose what to do generally or case by case.
Friendly,
- Michael