It does not matter which is the hen and which is the rooster since both contribute genes for egg shell color. That's provided both the rooster and the hens have the right genes. But roosters don't lay eggs so you can't be sure what genes they have.
Marans are supposed to lay dark eggs, but some Marans lay darker eggs than others. There are a lot of different genes that affect the brown on egg shell color. That's why you get so much variety in the brown color from different chickens. If your Maran hen is laying dark eggs and the rooster came from the same flock, he probably has about the same egg shell color genes as the hen.
The real problem comes in with the EE rooster. The genes for the blue egg gene come in a pair. Both mother and father contribute one of that pair. That gene is either blue or white for the base color. Since blue is dominant, if just one of those genes from either parent is blue, the hen will lay a blue or green egg. Green is just brown on top of blue.
EE’s are generally mixes. You’re usually not sure of the genetic background. It’s possible your EE’s have both blue genes in that pair, but it is also very possible that an EE has one blue and one white gene. It's also possible that an EE does not have any blue egg genes. If they are split, you never know for sure if they passed on a blue gene or a white gene until the hen lays an egg. Since roosters don’t lay eggs, you never know for sure about them.
If you cross a chicken that is split for the blue/white egg shell gene with a chicken that does not have any blue egg genes like your Marans, about half the female offspring will lay green eggs. About half the male offspring will not have the blue egg gene. If their mother was split for one white and one blue and the father was either split or didn’t have any blue egg genes, it’s very possible the rooster does not have any blue egg genes. It doesn’t matter if the rooster came from a hatchery or an individual unless that individual knows enough about the genetic background of their flock to be sure the rooster has the blue egg gene.
So I think your best bet to get olive colored eggs is to mate the Maran rooster to EE hens and only hatch blue or green eggs. That way you know for sure you have at least a 50% chance of getting offspring with the blue egg gene and the pullets should lay pretty dark eggs.
