Same issues for me too… when I mapping button 5 (X) it appears like B1…
and when I mapping button 6 (A) it appears also B1 !!
This is the all mapping i checked :
Real button on T flight // what happen in FSim :
F2 = B4
B2 = B2
F1 = A
B1 = B5
= F2
= A
= Y
= B2
Throttle = F2
select button = B
start button = Y
Next = A
Prev = X
B5 = B5
Y = B2
B = F2
A = B1
X = B1
B3 = B3
B4 = B4
back throttle button = F2