Hi Demonis, you should be able to transfer variables from Matlab to EditFEKO with current version of FEKO Suite 5.2 (though you can not do this with CADFEKO right now). In another word, your structure needs to be built solely inside EditFEKO with those cards, if the variables to be transferred are geometry-related. I do know that there are many FEKO users successfully implemented this process for optimization or sensitivity analysis. Two typical papers are attached and hope they are useful (another one with link below). Please let me know if you are interested in obtaining some simple demo examples for variable-transfer from Matlab.
BTW, as a side note, if your purpose is not to develop GA algorithm, you can just use the GA toolbox with Matlab to make things easier.