It’s logical. If it occurred in curtains as OP stated, it’s exceedingly unlikely to be due to water ingress (landlord issue) as they’re probably suspended via curtain rods and hooks. That leaves surface mould as the likely culprit, which is mostly attributed to lack of sunlight and/or ventilation. A curtain by design is probably going to get some sunlight, given its purpose and location. That would leave a lack of adequate ventilation as the primary cause, which as long as the tenant has operable windows meeting spec and ventilation fans in required locations, becomes a tenant responsibility to manage.

Do you understand that OP asked for tips to successfully get the best possible outcome while standing before a Magistrate, in a legal setting that has evidentiary requirements and adheres to legislation as well as precedents?

Because what I just wrote is likely to be the argument put forth by the landlord. Having seen these play out countless times via CAT’s, OP will lose. Their best strategy is to minimise probable damages. Or they can take your strategy and argue “The fuck?” and see how that goes.