Hi Simon
This is information from the EASA FAQs on this topic - found by using this link (https://www.easa.europa.eu/en/the-agency/faqs/air-operations?check_logg…) with the search term "Reduced Rest". Hopefully this helps.
Question: Reduced rest CS FTL.1.235(b)(3)(ii), (see also ORO.FTL.235 (c) and (e)): Is it possible to reduce the 14h rest away from home base following an FDP involving a 4-hour time difference or more?
Answer: No. CS FTL.1.235 (b)(3)(ii) does not foresee a reduction of the 14h rest away from home base to compensate for time zone crossing.
ORO.FTL.235 (c) describes the conditions under which the minimum rest periods according to ORO.FTL.235 (a) and (b) may be reduced.
ORO.FTL.235 (e) establishes the rest periods to compensate the effects of time zone crossing.
Additional rest periods to compensate the effects of time zone crossing shall be specified in flight time specification schemes.