well, you might find it easier (both short & long term) to return a # to the cells in your matrix (I6 onwards)
the above means your CF rule can be based on the number in the cell, this will also future proof against calculations you may choose to do latterly based on "colour".
with the above in mind... based on your screenshot (files are much better as people don't have to guess at cell references / contents, particular when using merged cells)
you should then find you have 0s, 1s, 2s & 3s... where 0 is "nothing", 1 is Engineering activity, 2 is PM activity and 3 is QC activity.
if you wish to, apply a custom number format to this range of ;;;@ and the numbers (schedule key) will disappear from view (they're still there, obviously)
then apply your CF rule based on cell value = 1, 2, 3 etc...
edit: for ease of reference I've added a working example with the above in place...
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