es and es_ES are identical, I propose we remove es_ES

Hi @Aaron Carlisle (Blendify) ,
I'm the translator of the UI into Spanish (one of the few languages that has been consistently maintained throughout these years), I've handed it alone since 2011, and a couple of times people tried to jump onboard to help, but unfortunately they ultimately never did any significant contribution, for different reasons I think.
I understand what you are looking for with these changes, and it could be a good thing, if done properly.

@Bastien Montagne (mont29)
I've found the "Cycles" string used for the render engine name is still used as the name of the Cycles F-Modifier, displayed in the UI when you add one of those.

I've also found:
"Axis" string is sometimes used as a plural word. (Should be "Axes" in such cases).

"Mirror", not relevant any longer. Thanks!

Currently (as of hash: rB0ee75698d05e downloaded today) the tooltips (showing both tool name and description) for the Tools icons in the 3D View are showing untranslated.
I remember I have translated strings for the tools names and tooltips, but they are not showing there.

"Path", in the context of particles appears in the Render > "Render As" dropdown option (and respective Options Panel Title).

*on particles Parent/Child:
There is a difference in that child particles are "derived" or "interpolated" particles, created and related not to a single parent particle (and its properties), but to several parent particles. I mean, "Parent"particles are particles which are fully independent on its own, but the "child" particles are not standard particles that have been attached to the main ones, in some sort of object hierarchical relationship, but instead are interpolated particles that do not even have their own parameters and therefore use the weighted parameters of nearby main particles to just exist.
So, it's not the same type of hierachical relationship users know from object parent/child relationships, and believe me (at least in Spanish) the particle parent/child terminology used for standard object hierarchies looks weird for this kind of stuff. :-/

Thanks Bastien!
God to see progress in this front. :)

@Bastien Montagne (mont29)
I know we should try to simplify things where possible, but currently there are some quite visible problems with strings being assigned in a too liberal way to different things.
At the very end of T43295 I've stated a lot of cases I've found while starting to translate 2.8 strings, some of the reports are the same as the ones in this issue.

Hi there!

Thank you Bastien!

I summarize strings with ambiguous uses here (sorry for the multiple posts, just thought it'd be easier to keep them all in one message):

yes, I assume that's the case.
just that I think the new version should not be released with this parameter not translatable
I hope it could be fixed before final release

I've found another string, so I summarize them all here:

I've just detected that the string:
"Clearcoat Roughness" does not exist, instead there is a "Clearcoat Gloss" string (the opposite concept?), that exists but it's not in use!
:-/