Straining is risky, and I suggest you avoid it if at all possible. What frequency were you trying to reduce? What exactly do you mean by “chronic diarrhea?”
A typical J-poucher has 4-6 soft stools per day, neither liquid nor hard. 10 days after take-down things would typically be busier.
It’s easier to prevent a sore backside than to repair one. People have many favorite creams - I had perfectly good results with plain, essentially odorless zinc oxide, applied *after* every BM, to protect the skin from the next one.