Do any bolt holes in the block extend into the water jacket? Manual says to only put oil on head bolts, but got me thinking about what needs sealer. My guess would be timing cover bolts.
like physically into it? no, the water jacket is separate from any bolts. Only put stuff on bolts if it tells you, such as the oil on the head bolts, by putting a thread locker or sealer you are changing the torque applied to the bolt and will affect the rebuild in terms of longevity and reliability, (Toyota 7mgte was plagued by this from the factory as they head bolts weren’t torqued down correctly so they all have head issues.
When in doubt, don’t put anything on them.