Hello Ondrej,
saving the employment fraction should work in the e-recruiting standard delivery. At least I am not aware of any release where SAP messed this up . Only tricky part here is that the application does not store the customizing key of the employment fraction in infotype 5126 but the working hours.
When the data is saved the application gets the working hours from the employment fraction customizing table and puts it into the infotyp. When the application reads the data for the requisition the hours are converted back to the employment fraction. Please ensure that in the customizing each employment fraction has as number of hours assinged. While the actual value does not really matter the value has to be different for every customizing entry as otherwise the conversion of stored hours into the correct entry will not work.
Kind Regards
Roman