Hello Demian,
CodeWarrior for ETPU supports bitfields.
I noticed there is missing .B in your usecase:
Est.B.B1 = 1;
Note:
if you expect reversed bitfield allocation please check pragma below:
<CW eTPU v10.x>\ETPU\Help\PDF\eTPU_Build_Tools_Reference.pdf
#pragma reverse_bitfields on | off | reset
Hope it helps.
Stan