Me too got a prompt reply from RE when I asked about the stuck lifter with the same answer although they had not heard of a stuck lifter till now.
I think my second idea is a no go. Thought about it later and I feel that can make the lifter even harder so only way is by loosening up the rocker plate bolts. Just don't loosen up too much, a wee bit should be ok I think. But yeah, no one would like to run around with loose rocker bolts.
Pin is anyway on the exhaust cam and as you have already mentioned the flames from TB so that confirms the inlet valve. So nothing to do with the auto-decomp. Is it possible that you might have a bent valve?
Are you on stage two/three, working on the head flow?
No problems Guru Ji, will post the manual in a day or so.