In BAL-29 bushfire areas any of the seven timbers classed as "bushfire-resistant", as listed in Appendix F, Table F1 of AS 3959:2018, can be used for external wall cladding. Not all seven may be readily available in all areas as cladding, but blackbutt and spotted gum are obtainable - refer Boral data sheet here http://www.mym.com.au/library/file/147/Timber_Cladding.pdf.

On the net you will find various treatments that can be sprayed onto wood to treat mould. However, mould is essentially a surface phenomenon that doesn't affect the strength of timber, and it seems appearance is not an issue in your case. Simply increasing ventilation under the floor should prevent further mould growth without the need to treat the existing mould. Providing improved ventilation will remove moisture rising from the ground, which is creating conditions for mould to grow.

The presentation of the data is perhaps a little confusing. As you say, only seven species are listed in Table F1 of AS 3959 as "bushfire-resistant" according to the test described in Section F2 of the Standard. Other species were in the process of being tested at the time our drop-down information tag was written. However that information needs updating since only the seven species listed in AS 3959 passed the test, and no further tests are planned in the immediate future.