diff --git a/model_manager/utils/repository/training_repository.py b/model_manager/utils/repository/training_repository.py
index 1095b3e..228f7a7 100644
--- a/model_manager/utils/repository/training_repository.py
+++ b/model_manager/utils/repository/training_repository.py
@@ -15,21 +15,16 @@ from sientia_do.operations.df_preprocessor import load_data
 from sientia_do.operations.normalization import MinMaxScaler, Z_Scaler
 
 from model_manager.sientia.metrics import mae, mse, r2
-from model_manager.sientia.models import DataPreprocessor, LinearRegressionModel
+from model_manager.sientia.models import (
+    DataPreprocessor,
+    LinearRegressionModel,
+    _frontend_date_format_to_strftime as _frontend_format_to_strftime,
+)
 from model_manager.sientia.utils import split_train_test
 from model_manager.utils.models.train_model_params import TrainModelParams
 from model_manager.utils.models.train_model_result import TrainModelResult
 
 
-def _frontend_format_to_strftime(fmt: str) -> str:
-    """Convert front-end date format (dd/MM/yyyy HH:mm:ss) to Python strftime (%d/%m/%Y %H:%M:%S)."""
-    if not fmt:
-        return fmt
-    out = fmt.replace('yyyy', '%Y').replace('MM', '%m').replace('dd', '%d')
-    out = out.replace('HH', '%H').replace('mm', '%M').replace('ss', '%S')
-    return out
-
-
 def _ensure_date_column_parsed(data: pd.DataFrame, params: TrainModelParams) -> pd.DataFrame:
     """If date_column and date_format are set, parse the column as datetime to avoid comparison errors downstream."""
     if not params.date_column or not params.date_format or params.date_column not in data.columns:
diff --git a/tests/utils/repository/test_training_repository.py b/tests/utils/repository/test_training_repository.py
index ce8f0da..c3ed4b5 100644
--- a/tests/utils/repository/test_training_repository.py
+++ b/tests/utils/repository/test_training_repository.py
@@ -1127,9 +1127,10 @@ class TestExtractModelEquationPolynomial:
 class TestFrontendFormatToStrftime:
     """Tests for _frontend_format_to_strftime."""
 
-    def test_empty_returns_unchanged(self):
-        """Empty string is returned as-is."""
-        assert _frontend_format_to_strftime('') == ''
+    def test_empty_or_none_returns_none(self):
+        """Empty string or None returns None (same behavior as models module)."""
+        assert _frontend_format_to_strftime('') is None
+        assert _frontend_format_to_strftime(None) is None
 
     def test_dd_mm_yyyy_hh_mm_ss(self):
         """Converts dd/MM/yyyy HH:mm:ss to strftime."""