I opened Rhino 9 WIP today and was greeted differently than normal…
I have never used anything other than plan English Rhino.
So it decided to be polish today or something? What language is that?
I had to open Rhino 8 to figure out where to change the language and when I did it appeared Czech was my new thing… So now I have started learning it on DuoLingo in case it pops back… 
Navigating the settings panel in a different language wasn’t an easy task.
This appears to be a bug introduced recently - several posts on it here…
This is funny. Sometimes 1-2 buttons of my Rhino 7 change to Deutsch for no reason.
Still, changing everything to Czech language is kind of readable to most Westerners. Imagine if it was Suomen kieli, Japanese or Bulgarian language. 
Only the tooltips I suspect. Known bug with V7 caused by copying butttons and modifying them
The WIP language bug being reported is completely different.
I will have to check the next time this happens.
Custom icons sometimes get “Macro 06” (or another number) random text for the tooltip, deleting my custom text.
Yep, all known phenomena…
Looks like a bunch of alien hieroglyphs dear God
Which version of the WIP are you using? The bug was supposed to be fixed in the 2026-04-28 release. This new update installs a Tsjech (?) version instead of English - #11 by brian
Perhaps the issue could be fixed by shipping several different versions of Rhino 9, each consisting just a single language. Language packs in many programs, operating systems and dictionaries are typically downloaded separately and are not mandatory. The file size is also reduced that way. Some video games also use that approach.
For example, I can delete or add separately any available language on my Samsung phone.
That’s the way it’s been up to now.
The new system was designed to make all the languages accessible without having to do that.
Here is another example from today. I was forced to delete this German text regularly, but it’s quite stubborn and appears all over again after some time. 
I just replaced the icon (a copy of a default icon) with a new empty icon and put the link to the script for the LMB inside, leaving the RMB field empty. I see no issues for the last few minutes.
Again, this has nothing to do with the new system of languages in the WIP (what this topic is about) and the tooltip problem in V7 which is a known problem that will never be fixed.
That known bug will never be fixed in Rhino 7 or Rhino 9 WIP? Looks like the latter has another, more serious bug with the localization, in addition to the old one.
Again, to repeat myself for the nth time : this.is.not.the.same.bug…
I wrote exactly that above. A new bug of the same type related to unwanted change of localization have been introduced now. The difference is that now it’s a lot greater than before.
Have you personally experienced this bug?
It was in one week’s build - the first one where the new system was turned on - and has already been fixed. Remember, this is a WIP.
Do you know what the change actually does?
Prior to the change if one wanted to install additional languages, one had to go into Windows>Programs and Features and go through Change>Modify, and check the languages you wanted to add; then they would get downloaded and installed. Only after that would they be available in the dropdown in Options>Appearance.
The new system simply now shows you all the possible languages for Rhino in the Options>Appearance dropdown. If you choose a language that isn’t already installed, when you close and restart Rhino, it will automatically download and install the language you want. No more need to go through Windows>Programs and Features. Otherwise everything is the same.
Again, this has nothing to do with the V7 tooltip bug (already gone in V8 BTW), which as AFAIK, is not actually a localization error pertaining to what language packages you had installed. The tooltip languages (all of them) seem to have been hard-coded into the toolbar system independently of the installed languages. Which is why when you got the bug, you could get tooltips in languages you might not even have installed like Czech or Chinese.
It’s a welcome news that the bug with wrong localization of certain tooltips have been fixed in Rhino 8 (and most likely Rhino 9 WIP).
As for the new bug related to the general localization in the latest WIP, I haven’t experienced it personally, because I work with Rhino 7. However, I do read in another topic from today that another person had such an issue with the latest WIP.
That remains to be seen if it is simply a hangover from the bug that was fixed. Normally the path set for folder for where the localized template files are located does change when you change the language - I tested here and that works - but if you have set a custom template as your default that is kept along with the target folder it’s in. So I will wait for the response from the OP in the other thread as to whether that was the issue or not. Also what version of the WIP they were using when this occurred.