There should be a brief pause/disable of ALL scoring when a bonus ball is being added. “Bonus Delay Relay”, something like that. If you get the fifth spin of the spinner (add bonus) and immediately also hit a lit bonus rollover switch, the rollover should NOT score unless the Add Bonus delay is complete. All bonus lights should also temporarily turn off during Add Bonus delay.
I know it’s not exactly what/where you’re talking about but might be related.