Its a challenge to even find the torque spec for those bolts in Elsawin - its not included in the timing belt section, but a separate bit just for the pulley. Spec is only 22Nm, which is surprisingly little actually. It doesn't say to replace them either. I think thread lock would be a very sensible idea though.

Mine had quite obviously been reused by the previous owner/garage. Heads were chewed to bits and 3 were a bugger to remove.
Ordered replacements off TPS - look like there is some coating on them to lock/hold in place