I cannot show a series of steps to reproduce it, but I am sure there are several bugs 
in the dialog localization.
I encounter problems when I design dialogs in My Macros with the IDE (preparing an 
extension). This has appeared on different projects and also before version 3.1.1.
 
Suppose you design some complex dialog library (several dialogs, each with several 
and various controls).
You test it with your code. Then you reopen the IDE to change something : add or 
suppress a control, or rename it, or add another dialog, or delete another, etc. 
Maybe also add another language.

When you test again you may see some texts of a dialog replaced by for example 
&874.DlgSel.CurrentState.Label which means the localization mechanism cannot retrieve 
the corresponding string.
Then you close OpenOffice, and during the closure you get a crash message of 
OpenOffice.
If you read the DialogStrings_xx_XX.properties you find errors like duplicate lines 
or lines out of the nummbering order, or missing lines.

These bugs may not appear on very simple dialogs, but they do appear sooner or later 
when you create really useful dialogs. It is very difficult and time consuming to 
correct the errors, and they may reappear each time you edit a dialog of your 
library. So in the current state, it is impractical to use for a professional project.

IMHO the designer of dialog localization mechanism should review carefully its code 
and find out why there are errors when the files DialogStrings_xx_XX.properties are 
re-written.