MACR will be issued only when crew are MIA (usually over enemy territory or over sea, sometimes in rough terrain).
In your case, the crew fate (KIA) was obvious so there was no MACR but an accident report.
Check this page
http://www.aviationarchaeology.com/s...y/Aug1944O.htm
to see a list of the accidents outside USA. This page is for August 1944, there is one for each month of the war.
THe only deadly accident I found on these list at Rennes was on 28 August 1944
Date: 440828
Aircraft type: UC-64A
Aircraft number: 43-35396
Unit: Hq 100FW
Base: A27 (Rennes)
Airforce: 9th
Fate: KCRT
Pilot: Patterson, Robert A
Country: FRA
Place: Rennes/A-27
KCRT means Killed, CRashed on Take off
An UC-64A is a second-line aircraft. It has only one engine and is very different from a P-38.
You may check the accident lists of 1945 too.