Unfortunately I think that you may not be able to rescue either of the tinctures you have already made. The one that has mould on it, has mould all the way through it, there is no straining that off. If you made the other batch in the same way, it is likely it will follow the same path due to the water content in fresh violet leaves. You could always strain it in the same way you did with the first one and see if you get lucky (don’t squeeze it too much this time), but my guess is that you need to use a very high alcohol percentage (like 70-90%!) in order to keep that watery tincture preserved.
If you can get your hands on a strong enough alcohol, then what I would suggest is to try again with this. If not, I would harvest leaves and make tea every couple of days. Which I know is time consuming and limiting in terms of how long you could do that for unfortunately.
With that being said, I hope the second batch you had made works okay and does not go mouldy.