Changed to UI culture by default for web output

Duplicati/Library/Localization/LocalizationService.cs

@@ -98,6 +98,20 @@ namespace Duplicati.Library.Localization
             }
         }
 
+        /// <summary>
+        /// Gets a localization provider with the current UI language
+        /// </summary>
+        public static ILocalizationService CurrentUI
+        {
+            get
+            {
+                var lc = LocalizationContext.Current;
+                if (!string.IsNullOrWhiteSpace(lc))
+                    return Get(new CultureInfo(lc));
+                return Get(CultureInfo.CurrentUICulture);
+            }
+        }
+
         /// <summary>
         /// Gets a localization provider with the OS install language
         /// </summary>

Duplicati/WebserverCore/Middlewares/LanguageFilter.cs

@@ -18,6 +18,7 @@
 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
 // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
 // DEALINGS IN THE SOFTWARE.
+using System.Globalization;
 using Duplicati.Library.Localization;
 
 namespace Duplicati.WebserverCore.Middlewares;
@@ -30,7 +31,7 @@ public class LanguageFilter : IEndpointFilter
             ? LocalizationService.ParseCulture(locale)
             : null;
 
-        using (ci == null ? null : LocalizationService.TemporaryContext(ci))
+        using (LocalizationService.TemporaryContext(ci ?? CultureInfo.CurrentUICulture))
             return await next(context);
 
     }

Duplicati/WebserverCore/Services/SystemInfoProvider.cs

@@ -273,7 +273,7 @@ public class SystemInfoProvider : ISystemInfoProvider
     public SystemInfoDto GetSystemInfo(CultureInfo? browserlanguage)
     {
         browserlanguage ??= CultureInfo.InvariantCulture;
-        var currentLanguage = LocalizationService.Current?.Culture.Name;
+        var currentLanguage = LocalizationService.CurrentUI?.Culture.Name;
         if (string.IsNullOrWhiteSpace(currentLanguage))
             currentLanguage = CultureInfo.CurrentUICulture.Name;