‘Venial from the event’: any sin that actually obtains pardon
‘Venial from the event’ means any sin that repentance actually clears and God pardons.
In that loose sense it is not set against mortal sin as such, but against sins that never are forgiven.
Latin
II. Peccatum veniale ab eventu ipsis dicitur peccatum quodlibet, quod per poenitentiam expiatur, & actu veniam a Deo consequitur, quantumlibet alioqui in se grave & atrox fuerit. Adeoque peccata hoc sensu venialia non opponuntur absolute peccatis mortalibus; sed eis solum quae reipsa nunquam remittuntur; ac per hoc ad mortem perducunt aeternam.