I guess that the AC on R109 must be just leakage through ZR101 and/or being sourced from the IC (a bit of pulling up?) through D105... remember it'll be "pulsed" or very ripply DC on pin 12 of the IC, as C118 charges from the mains and is then discharged by whatever our mystery current sink is.
If there's more voltage on R150 (681 ohms?) than on R106, doesn't that indicate a lot of current flowing out of pin 7? That seems very odd. Or could it be flowing through the gate of a damaged Q103?
Your measurements in #23 give a current of about 370uA (RMS) - which should be enough to start the IC, which has a maximum startup current of 250uA, according to the datasheet. I'm probably mistaken here, but shouldn't these add up to 230V, not 130?