I don’t have time to lookup the thread for a link to the discussion but it’s confirmed that these plots marked as roads still generate footfall and otherwise act as part of the beacon and settlement, as long as the beacon is not “bridging multiple settlements”.
You may have to touch builds on more than one plot to join to or expand the settlement this way, if things are only 1 plot thick.
6 plots combined in adjacent columns so a 6-plot vertical will create a valid settlement in a single plot column. “5 other plots touching” implies they have to connect physically but they can actually not touch by vertical offset.
As long as they’re in the adjacent pot columns, though. This basically means you’re always looking at a 3x3 to determine this status no matter where the individual plot is in the shape of your beacon.
EDIT: actually easy to find it in my history, here’s the discussion from the time of the change with pictures and corrections and all:
No worries. The main thing to remember is the only difference between a road plot and a regular plot is that road plots can’t force settlements to merge. For all other intents and purposes, including footfall, they work the same.
The only problem with road plots is when they’re in a ‘bridging multiple settlements’ state (because they can’t force a merger) and in those cases you have to debug it by either removing plots so it doesn’t bridge multiple settlements, or adding plots so it’s no longer a road, which would force a merger. That only seems to happen with thin, long series of plots (1 by X by 1 roads primarily, with X being length).
So those corner road plots (when they happen) have no effect at all.