Try a forum search for
"camshaft endplay"

It has been deemed harmless.

Quote from: gerharddvsnow the tappet cover is leaking oil

Is it possible that it was torqued down TOO hard?  I have never used a torque wrench on the cover bolts - mostly because like you I couldn't figure out how.  But the cover is just that: a cover.  As long as the bolts are tight enough to create a good seal and to not come loose they should be good.

Another possibility is that the gasket was not quite lined up, and it got pinched between the cover and the top end.  You can do a visual inspection / feel with your fingertip around the entire perimeter to make sure the gasket lines up with the edge of the cover.

Where is the leak happening?  If it is around one or more of the 4 semicircular tabs on the gasket, pull the cover and reseat it.

One last thing - did you use any gasket sealant?  If so then perhaps it went on unevenly and left a gap.  If not, then consider using it to seal the gasket to the cover (NOT to the engine top end) which will simplify disassembly / reassembly in the future.