Presenting the event in the same game, to the same AI, at the same time, produces repeating results:
https://forum.paradoxplaza.com/forum/threads/events-outcome-predetermined.1387698/#post-26541064
As this one here is triggered by a decision, simply select it at a different time after reloading.
Otherwise the probabilities seem to be as
@MattZed described.
num_of_available_civilian_factories is
_nTotalGeneralFactories - _nLendedGeneralFactories - _nUsedGeneralFactories, which closely matches the first number in the construction tab factory tooltip:
View attachment 652839
which is
_nTotalGeneralFactories - _nDamagedGeneralFactories - _nLendedGeneralFactories - _nUsedGeneralFactories. Unless the AI country has a huge number of damaged CIC,
num_of_available_civilian_factories is probably almost always 0. Both the difference to the tooltip and the use of this trigger instead of
num_of_civilian_factories_available_for_projects (which is
_nTotalGeneralFactories - _nProjectFactories - _nConsumerGoodFactories - _nLendedGeneralFactories) should be reported as bugs.
Assuming the relation to the target country is above -50 and they don't have a lot of damaged CIC the weights (probabilities) are currently:
- moderate investment: 10 (16.6%)
- no investment: 50 (83.2%)
- no investment ever: 0.1 (0.2%)