Hi. Done a bit of curing, but not this recipe. White mould is no problem, give it a wipe with vinegar soaked cloth to get rid of it if you feel the need. If the mould is darker then give it a good sniff. If it is 'bad' mould then you will know by a very bad smell.
Get the white mould all the time curing beef, chorizo, lomo, salami - I think it is penicillin, but might be wrong.
Only time got the really nasty dark mould was taking a short cut on some bresoala. Did not dry thoroughly before wrapping in muslin.
Based on your picture, I would say that is completely normal and expected. I have eaten and seen much worse
Don't use balsamic or malt - something like red, white or cider vinegar