Hi Werner,
I have talked this over with development and we agree with your synopsis. Although a decimal type is not actually a numeric but is an object reference instead, it should not be too difficult to allow decimals to be used in standard COBOL arithmetic statements.
Can you open up a support incident with Customer Care and mention my name in the description so that it is routed to me? I will then open up an RPI and we will look at addressing this functionality in a future release.
Thanks.