Those limitations are typical on many types.
I would recommend that you download a copy of ICAO DOC 8168. Typically the limit for an ILS glidepath is 3.5º, above this it is considered a steep glide path angle and it is recommended (from a procedure design point of view) to use this steeper glide path only for obstacle clearance. There are a lot of considerations when flying a steeper angle. I.e. extra margin in case of go around, engine spool-up time etc. Airbus has published some 'getting to grips with...' documents. Getting to grips with CAT2 CAT3 has a lot of useful information about aircraft certification, but it is a bit dated. Hope this helps.