However - an ice accumulation effectively "redesigns" the aerodynamics so that the amount of fuel the controller thinks correct is now too much! Ergo, stall, lack of acceleration, etc
Oh I wish that you hadn't left that so simple and thus feed Oluf with his ever so simple explanations.
It's true that with a significant amount of aerodynamic change (ice accretion) the fuel metering will not match the performance, but the signature is much more likely to be a mismatch in rotor spool RPMs N1, N2, N3 followed by a stall/surge. All of which are sure to be recorded on the various recorders, including non-volatile memory in the FADECS.
Add to this the extereme rareity of such non-mechanical damage events for in-flight scenarios (ground fog at ground idle is not part of this discussion).