Regarding CLN L608 SUMUM L179 COA...
The UK AIP gives
For flight planning purposes AWY L608 above FL 110, is
for westbound flights only, exceptionally ATC may clear
tfc eastbound.
The UK RAD has no eastbound restrictions.
The Dutch AIP gives:
Flights intending to follow L179 eastbound will have to acquire prior permission from Brussels ACC to fly above FL 110.
L179 is not AVBL for traffic with DEST EGKK, EGHH or EGHI. This traffic shall route via L610.
though strangely it does give a minimum flight altitude of FL100, even though the airway base is FL55.
The Dutch RAD has:
L179 SASKI-NIK Not available for traffic Dest. EBBRTMA (EH**2007)
The Belgian AIP is silent, and its RAD has no eastbound restrictions.
The CFMU Environment section on the CIA gives L179 available FL55 to FL195, but L608 only FL55 to FL115.
IFPUV seems to permit eastbound flights up to FL110, and indeed my FPL was accepted at FL090 and CFMU's flight route was CLN LOGAN SUMUM SASKI COA.
So I think, LG52TYT, you're either mistaken about the Brussels area destinations, or your computers are inconsistent with CFMU's and the RADs.