"The average contrast is 0.65 unless otherwise stated. The ISO recommendations should be followed if possible. ** The times for Ilford Delta 3200 have not been tested and are a guide only.
The RODINAL 1 + 100 times are only recommended for use in hand tanks. There should be a minimum of 250 ml’s of solution for each film in the tank." Agfa Chart
A key is the average Agfa recommended contrast is 0.65. This may work in flat light but is way off Kodak's recommended 0.56 CI for a diffusion light source.
My phone-app version of the Massive Development chart recommends that if you're rating at EI64, then you should use Rodinal (1:100) for 21 minutes at 20*. If you're set on (1:50), then that may not work.