Ref Alert Height DA DH and autoland
For US operators,... See FAA AC120-28D. Normally, Alert Height (that is Operational use of AH, ...versus any value potentially considered for aircraft design or certification considerations) is not set above 100' HAT. That's because the higher the alert height, the less conservative the safety application due to the continuation consequence. Conversely, the lower the AH, the safer the application, because the result is a go-around for a mode reversion or failure.
Further, "Irregular terrain" considerations should typically be assessed for each aircraft type and AFDS system used, while in weather conditions better than when Cat II or III minima are actually needed. See also AC120-28D and AC120-29A.
The "caution note" on the EGGW SIAP is most unusual, and would be much better addressed and placed in any ops authorization to use that specific procedure, so as to remove any such interpretation ambiguity. That's why specific "Irregular Terrain" assessments, qualifications, and authorizations are typically used for both autoland (and HUD AIII mode) for various aircraft/system types, and for US based ILS or GLS runways with underlying irregular pre-threshold terrain. Again,... See FAA AC120-28D section 6.2.5, 10.7, and Appendix 8.