The only Rotax powered Tecnam presently available for IFR is the
P2006T.
This is EASA IFR certified and with NO restrictions in the use of either Avgas 100LL or EN228 spec MOGAS (and up to 10% Ethanol) regarding altitude or temperature, or anything else for that matter.
In the UK the restrictions were written as CAA Airworthiness Notices (now CAP747 Generic Concessions) before the Rotax 912S was born.
CAA Safety Regulation Group Surveyors agree that the Type Certificate Data Sheet takes precedence over GCs.