I checked with them, seems like you are correct, they have not changed the error message. The rejected shares are due to crappy card quality, not playing nice with the strap. Another thing that i seem to notice is, XMR-Stak was discarding Invalid shares, but logging them regardless, which were equivalent to Hardware Error (HW). But on this fork, instead of being HW, its a Rejected share. I have used the sgminer-gm-5.5.5, and it was doing HWs, instead of rejected shares. Pretty confusing.
I will be checking for the 30/60s stuff for the API.
Thanks for reporting back! In the current version our miner doesn't have cpu verification of the hashes, probably the only one that doesn't. We just send everything to the pool and let them check the shares. We're just about to add the cpu verification parts though, so when that's in place we will be reporting bad shares as "HW errors" as well and not piss of the pool(s) when you push your mem straps too hard

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