Jak zamawiać przez FIELD z GROUP BY

Po prostu masz złą kolejność group by i order by;

...
ORDER BY
  FIELD( t.type, 'initial', 'commision', 'overpay', 'penalty', 'penalty2' )
GROUP BY
  t.type;

Powinno być:

...
GROUP BY
  t.type
ORDER BY
  FIELD( t.type, 'initial', 'commision', 'overpay', 'penalty', 'penalty2' );