Localizing Actipro Controls

I post this question in the Docking/MDI-Forum, but it reaches other controls too (here: the Ribbon Control).

With the SR-Class I'm able to customize the string resources, that are displayed in the user interface. I used the String Resource Browser to see the available string resources for the Docking- and the Ribbon Control. The target is to translate the displayes strings from English to German language.

I wondered, why this works sometimes and sometimes not. I'm able to customize the Options menu, that appears when clicking the arrow-icon in the right corner of a tool window (Dock, Dock as Document, Float ...):

SR.SetCustomString(SRName.UICommandCloseWindowText.ToString(), "Schliessen")
SR.SetCustomString(SRName.UICommandMakeDockedWindowText.ToString(), "Andocken")
SR.SetCustomString(SRName.UICommandMakeDocumentWindowText.ToString(),"Als Dokument andocken")

This works.It's also possible to customize some of the string resources of the Ribbon Control:

SR.SetCustomString(SRName.UICustomizeMenuItemShowAboveRibbonText.ToString(), "Ueber dem Menuband anzeigen")
SR.SetCustomString(SRName.UICustomizeMenuItemShowBelowRibbonText.ToString(), "Unter dem Menuband anzeigen")
SR.SetCustomString(SRName.UICustomizeMenuItemMinimizeRibbonText.ToString(), "Menuband minimieren")

When I start the application, the customized string resources are displayed. But other won't, although I've customized them in the same way.

For instance, with the following line I want to customize the Application Button of the Ribbon Control:

SR.SetCustomString(SRName.UIApplicationButtonScreenTipHeaderText.ToString(), "My little App")

But if I start the application, the tooltip of the Application Button  is furthermore "Application button".

Same with the tooltips of the controls of a tool window in the right upper corner (Options, Pin and Close (the X)):

SR.SetCustomString(SRName.UIAdvancedTabItemCloseButtonToolTip.ToString(), "Schliessen")
SR.SetCustomString(SRName.UIToolWindowContainerOptionsButtonToolTip.ToString(), "Optionen")

Within the String Resource Browser I see several items with the string resource Close, Auto-Hide or Options, so I may made a  mistake and take the wrong string resource.

But even if I customize all these items, the tooltips were displayed in English. The string resources for the Ribbon Control in addition contains only one item with the string Application Button, so this should be the correct string resource. Also the tooltip for the QAT (SRName.UICustomizeMenuItemCustomizeQatText) stays unchanged in English, but the text inside the popup (SRName.UICustomizeQatMenuHeaderText) is customized. And so on.

Could you please explain me, where my mistake is?

Thanks in advance

Michael

Edit: the Version is v16.1.0632