Chronus :
Much too close for comfort.
Yes in ATC separation standards values , but from the air, over one Km away on crossing tracks is not really that " too close" .
As to the vertical , TCAS is designed to give you 3 or 400 ft , not more . It is not a separation tool it is an anti collision system. So here they got what TCAS planned.
One of the Belgian newspapers printed a map of the event ( probably from FR24) showing as I expected a very high rate of climb ( 2500-3000ft/min) of the A300 which initiated the RAs.