You could do that with a single command:
When I say: flaps [up;0;5;10;15;35;full]
Begin Condition : [{CMD}] Ends With 'up' OR [{CMD}] Ends With ' 0'
Press F5 key and hold for 0,01 seconds and release
Else If Text Compare : [{CMD}] Ends With ' 5'
Press F5 key and hold for 0,01 seconds and release
Press F7 key and hold for 0,01 seconds and release
Else If Text Compare : [{CMD}] Ends With '10'
Press F5 key and hold for 0,01 seconds and release
Press F7 key and hold for 0,01 seconds and release
Press F7 key and hold for 0,01 seconds and release
Else If Text Compare : [{CMD}] Ends With '15'
Press F8 key and hold for 0,01 seconds and release
Press F6 key and hold for 0,01 seconds and release
Else
Press F8 key and hold for 0,01 seconds and release
End Condition
Note the space for " 0" and " 5"; Without it, those branches would trigger for "10", "15", and "35" as well.
If not all keypresses for a single setting are registered, you may need to add a delay between each press.
You can press F1 while VoiceAttack has focus to open VoiceAttackHelp.pdf in your default PDF reader; That document has information on VoiceAttack's features.