- Renew has a minor bug that makes it heal for very slightly less than it should (if talented)
- Prayer of Mending has a bug that makes it heal for quite a bit more than it should (if talented)
- Improved PW:S has a bug where the percentage bonus is applied based on the base amount (not the total)
Details at the link. His formulas are wrong as written - he consistently writes things like
1.05*(1.05+1.10)*1.10 when what he means is
...but if you're familiar with the general issues he's discussing you will know what he means.