patch 9.1.0559: translation of vim scripts can be improved

Problem:  translation of vim scripts can be improved
          (after v9.1.0509)
Solution: improve documentation, add tests, include missing
          libraries for the Windows CI
          (RestorerZ)

closes: #15100

Signed-off-by: RestorerZ <restorer@mail2k.ru>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_gettext_utf8.vim b/src/testdir/test_gettext_utf8.vim
index bb46ca0..7862e39 100644
--- a/src/testdir/test_gettext_utf8.vim
+++ b/src/testdir/test_gettext_utf8.vim
@@ -1,20 +1,20 @@
 source check.vim
-" TODO: Why does this fail on MacOS 14 and Windows MSVC (Github CI)?
+" This fail on CI MacOS 14 because bindtextdomain() is not available there
+" (missing library?)
 CheckNotMac
-CheckNotMSWindows
 
 " Test for gettext()
 func Test_gettext()
   set encoding=utf-8
   call bindtextdomain("__PACKAGE__", getcwd())
   try
-    language ru_RU
+    language messages ru_RU
     call assert_equal('ОШИБКА: ', gettext("ERROR: ", "__PACKAGE__"))
   catch /^Vim\%((\a\+)\)\=:E197:/
     throw "Skipped: not possible to set locale to ru (missing?)"
   endtry
   try
-    language en_GB.UTF-8
+    language messages en_GB.UTF-8
     call assert_equal('ERROR: ', gettext("ERROR: ", "__PACKAGE__"))
   catch /^Vim\%((\a\+)\)\=:E197:/
     throw "Skipped: not possible to set locale to en (missing?)"