I fixed it!
The errors were as follows
serverrules.xml line 23 character 29 Was:
<cvar name="C&C_Walls.mix" value="No Wall Jumping."/>
changed to
<cvar name="C&C_Walls.mix" value="No Wall Jumping."/>
warnings.xml line 75 character 52 Was:
<help value="Counts how many logs there are for <playername>, and returns the 5 most recent ones."/>
changed to
<help value="Counts how many logs there are for [playername], and returns the 5 most recent ones."/>
BR reports no more errors. The warnings and serverrules plugins work again.