And if you comment out the unnecessary last part from the GROUP BY it will even start returning the resultset which seems reasonable:

SET @Pattern2 = N'

SELECT transmission_natlang ,modeltrim_name , technical_item_name_natlang , unit_natlang

<<@DynamicList4>>

FROM Test_2_11 a

GROUP BY transmission_natlang ,modeltrim_name , technical_item_name_natlang , unit_natlang

--,technical_item_name_natlang +''''+ unit_natlang +''''+ powerunit_natlang +''''+ value_primary

;'