Not at all, in fact many were proud to wear the buckle that they had worn for years, in the regular army, until there were ornate CSA style buckles available usually through the blockade from France or Britain.
I believe Jackson, Bragg, Longstreet and even Lee did the same, but were soon replaced by presentation swords and belts from a grateful state, or region. Lee was presented a beautiful sword & belt made in France from individuals in Maryland.
Many of the sword belts they possessed predated the Civil War... and majority had seen service in the US Army prior... They simply continued to wear them... same with older US inscribed swords...
The use of Federal officer muffin eagle buttons was also very common to find on Confederate Officer frocks....