I agree 'not smiling' words 'will endeavour' and 'where possible' remind me of the following:
You are entitled to 15 hours minimum rest at home base but this can be changed to 12 due to delays
and
The maximum UNMINS we carry is now 6, but of course this can be changed to 8 due to disruption.
These refer to current conditions, I am sure there are more, but I just cant think of them.
Either way, I think the words 'where possible and will endeavour' should be banned from any EBA.