Not sure if you're still having this problem, but I was as well but got a solution working. For reference I am running a physical FMC with FTD instances on 7.0.4.
The way I got EIGRP into OSPF was creating a Text Object under FlexConfig. You need to put your OSPF AS as a string variable. From there under the FlexConfig Object, you'd call on the text object you just created and input your normal redistribution command syntax.
So it looks something like this:
Variable type: “ospf 1”
router $RouterOSPF (variable name that was just created inserting Text Object of RouterOSPFAS)
redistribute eigrp 3157 metric 2000 subnets