Desperately seeking advice on my Trident Maple Forest

Hello everyone
I am new to bonsai and this is my first bonsai it was a present that my son’s gave me for my birthday and something that I have always want to learn unfortunately when I received it the base came all cracked and they sent me a new and I got to keep the first so I went and bought a new temp pot for it as well as new soil which is Akadama mix. I live in Souther California zone 9 and lately it’s been really overcast and constant drizzle about two days ago Instarted noticing these black spots on them and I don’t have enough knowledge about what it is or even how to fix or if I can even save them, I need to buy some books but there are so many and don’t know which ones are best for a beginner. Any advice that someone can give me would greatly be appreciated I have been very ill and going through chemo so this is such a wonderful hobby since I have always been so fancinated with bonsai just never has the courage until now. I am posting some pictures that I took yesterday. Thank you again for any advice. Sincerely GinaMarie

Looks like a fungal disease. At a minimum, keep the foliage dry and well ventilated. If it gets worse you’ll want a fungicide.

Thank you so much cable I had reposted this and some members told me the same thing, it’s really great to have so many people with so much knowledge ty!