Not really sure what you did there with the carb adjustments, but the fact it needed more pump shot suggests you made it leaner. I'll guess that adding timing to the 15* at idle made it a better match for the mix. How much timing was added? 5*, 10*, 15*? No real danger, just less efficient burn in relation to pushing the piston down the hole with the most leverage.
Its better to get the timing about right, and then adjust the carb. Even using the factory specs, there's some expected adjustment. Say its 10* at 600, well then 12 or 14* would still be in expected range. But 10 + 15* is well beyond the range. Yes it will run at 25*. And I don't know if its 15*, just throwing that out there as an example.
Timing is about firing the mix so the burn develops maximum pressure at through the most efficient position of the piston. How long a mix takes to burn and develop pressure varies with combustion chamber, compression and heat, as welll rpm (hence the mechanical advance) and mixture (hence the vacuum advance).
