If you adjust the temperature adequately then your cold temperatures are no problem. Ederīs "Rezepte und Tabellen" (German book) says the original Rodinalīs temperature coefficient is 2. That means that if you lower the temperature by 10 degrees Celsius then you have to develop twice as long. To use your normal dilution and multiplicate by about 1.6 could be a good starting point for 14 C.

I developed in Rodinal at different temperatures, also at 14 C and everything was fine at every temperature. Unfortunately I donīt remember the time and dilution I took at 14 C. In contradiction to other opinions I found no optimum or especially good temperatur between 14 C and 20 C. Maybe somewhere over 20 C Rodinal becomes worse in grain, but I never tested that.