As far as I can see from the Bellini data sheet you dilute the concentrate 1+1 to get stock. For Fomapan 400 exposed at ISO 400 the developing time using stock should be 7 minutes at 20C, how does that compare to what you used? If you dilute the stock 1+1 the developing time should be 9.5 minutes at 20C. XTOL can be diluted up to 1+3, but Massive Dev Chart only goes to 1+1 for XT-3. The Bellini data sheet does not mention dilution of stock, but I would definitely test it out, at least to 1+1. Extending developing time will increase contrast, but you're probably aware of that.