If you add a style command to e.g. a toolbar, the full xlink name will be added to the appropriate toolbar xml file. For character styles it's xlink:href=".uno:StyleApply?Style:string=NAMEOFSTYLE&FamilyName:string=CharacterStyles". Other styles are structured identically.
The string NAMEOFSTYLE is replaced by the name of the style.
It's the name which is also visible in the Styles & Formatting sidebar deck and not an abstract name.
If the style has a German name when adding to a toolbar, it's not usable in non-German installations.
The other way round (English name in German UI) is only not working with character style "Default Style" (German: "Standard"), as far as I figured out.
In the following example, the English string can't be used in an German UI. The German string can't be used in an English UI.
<toolbar:toolbaritem toolbar:text="Standard" xlink:href=".uno:StyleApply?Style:string=Standard&FamilyName:string=CharacterStyles"/>
<toolbar:toolbaritem toolbar:text="Default Style" xlink:href=".uno:StyleApply?Style:string=Default Style&FamilyName:string=CharacterStyles"/>
The style name's arent language dependent unless they are set so in the XML file.
Created attachment 133850 [details]
On top: Formatting (Styles) toolbar, pre-installed in LO 5.5 / bottom: custom toolbar with the same styles
The attached screenshot shows 2 toolbars:
1. Toolbar on top: pre-installed Formatting (Styles) toolbar of LO 184.108.40.206 alpha0 which shows only English style names except "Betont" (emphasis character style).
2. Toolbar on the bottom: custom toolbar with the same styles, made by me with LO 220.127.116.11 alpha0 which shows the same styles, all paragraph and character styles are German but not the list styles except Numbered List 5 (German: Nummerierung 5). I renamed Heading 1-3 manually to Ü1, Ü2, Ü3. But in the XML file you can see that character style "Default" and list style "Numbered List 5" also have names (toolbar:text="Standard" + toolbar:text="Nummerierung 5") which were not added by me but from LO. I don't know why and when do LO add a name for a style.
Created attachment 133851 [details]
Custom toolbar, cloning the Formatting (Styles) toolbar
CPU-Threads: 4; Betriebssystem:Linux 4.8; UI-Render: Standard; VCL: gtk2;
TinderBox: Linux-rpm_deb-x86_64@70-TDF, Branch:master, Time: 2017-05-31_06:36:03
Gebietsschema: de-DE (de_DE.UTF-8); Calc: group
Forget point 1. in comment 2. The style entries of the Formatting (Styles) toolbar have short names except "Emphasis". Therefore it's clear that they are shown English.
But that didn't explain why some manually added styles get a name automatically. Can you reproduce that?
(In reply to Thomas Lendo from comment #4)
> But that didn't explain why some manually added styles get a name
> automatically. Can you reproduce that?
They get the same name found in the add command dialog for me. If you think there is a bug for manually added styles, please file a new bug report with steps so i can try and repo it.