I reckon they could have made it on SA22 on 15 Oct, 1045-1215.
That'd give us enough time for a semi-rural Leg 7 on 15 Oct, and an urban Leg 8 in Harare on 16 Oct.
According to flightaware, the teams took the correct flight to Harare from a connection in Johannesburg on October 15th:
SA22 JNB-HRE 1100-1219
And here's what I reckoned on the flight from Prague to Harare:
Swiss (LX) 1499 PRG-ZRH 1953 (10/14) - 2100 (10/14) (scheduled 1955-2115)
Swiss (LX) 288 ZRH-JNB 2243 (10/14) - 0906 (10/15) (scheduled 2240-0910)
South African (SA) 22 JNB-HRE 1100 (10/15) - 1219 (10/15) (scheduled 1045-1215)
Apologies for my "archived" Prague to Harare post above which is now outdated.