This is not a complete review.
First off, the title should be Cambodia UNESCAP / ASEAN Asian Highways, since UNESCAP does not recognize AH123.
Anyway, it looks pretty good, but I see the following changes:
AH1 should probably bypass Kampong Chhnang (
the old and new routes are both signed as National Road 5). I'm not sure about Oudongk, Battambang, or Sisophon, but all bypasses are designed as the thru route at both ends. But then there's
this in Sisophon, so I guess keep AH1 through town unless there's a good reason to assume this sign is no longer accurate. All of these bypasses are mentioned in
a 2015 presentation about Asian Highways in Cambodia.
AH11 needs several points at
E4 interchanges. Unless AH11 uses E4?
AH21 has a potential bypass around downtown Siem Reap, but I'm not seeing signs for anything.