Just something I noted, but....
there are different IDMT-curves (IEC), the most common types are the NI (normal inverse), VI (very inverse) and EI (extremely inverse) The formula for the mathematical trip time in seconds is:
t(sec) = a . k / (((Fault/measured Current / Set Current) ^ b ) - 1)
k = time constant or time dial
Just note that for a NI-curve your formula is:
t (sec)= (TimeConstant * 0.14
) / (((Current / StartingCurrentConstant) ^ 0.02) -1 )
To answer your question (in my opinion):
I'm not sure whether you mean that your tripping will be to fast or to slow in Argument C, but both (too fast or too slow) are not correct.
If I understand correctly, at Current A the relay will time for half of the time (15sec) and then with Current B it will time again (10sec), resulting in a total triptime of 25sec? (Too slow)
Or do you mean it will trip the moment the current change (15sec) because it is past the 10sec time of Current B? (Too fast)
For a too fast trip, you will struggle too coordinate with other feeders downstream, resulting in unnecessary downtime on a lot of feeders.
With a too slow trip you can damage the electrical equipment (Generators, Transformers, cables, switchgear, motors, etc.)
Argument D seems to be fine.
Sorry, I'm not aware of any documentation, I'm just thinking from a perspective out of the field