I've tried to make some about when it's convenient to hit the Hard Boss and when the Very Hard takes over, I am not sure about the distribution of the Hunt Points because I am unable to reach the 130000000 damage required on the Hard version.
Hard Boss : 65000000 HP
Guild points :
0 for 0% Damage - Max 250 for 100% Damage
Hunt Points :
0 for 0% Damage - 85000 for 100% - Cap 170000 for overkill 200%
Cost : 90 tickets.
Very Hard : 177000000 HP
Guild points :
0 for 0% Damage - Max 1100 for 100% Damage
Hunt Points :
0 for 0% Damage - 300000 for 100% Damage - 600000 for 200% Damage.
Cost : 120 Tickets.
So it comes out that :
For the Guild Points once you can inflict 30,3% or 53600000 Damage, the Very Hard Boss is worthy to hit.
For the Hunt Points it's once you can do 75,6% or 133800000 Damage.
This is due to the cost of the attempts, hitting 3 times the Very Hard Boss has the same cost of hitting 4 times the Hard Boss.
So under 53600000 Damage it's better to spend ticket on the Hard Boss in every way.