Before we get to the problem you think you have, let me go to the real issues :-) Or you can ignore what I say and skip to the bottom two lines for thoughts on your leaf issue.

Are you afraid to trim the low branches for some reason? Get those low branches off the tree, tie it to a stick for support, ALL the way up, not 12" from the ground only, lose the fruit and train it in a straight upward growth habit. I let my three grow to about 5 feet then snipped the top to force branching. Once it branches, let the branches get long say 3-4' tip prune them to force more branching cutting off branches that grow downward. This way you will be able to move around the tree and pick fruit easily as it matures.

Carambola start life VERY scraggly and you need to help it get strong. In 4-5 years with help from you it will be strong and give you more fruit than you and your neighbors can eat. If you want fruit today, go to Publix :-) If trained properly you can let it keep fruit when it's strong enough to not break or deform under the weight of the fruit.

That said, carambola are VERY disease resistant in so. Fla. and with your tree so low it's hard to tell if it's cat spray, yard spray, direct fertilizer burn or maybe something else spraying on it from say a neighbor, splashing from your roof or from your lawn mower debris landing on it. To me it looks like mineral oil spray burn. Have you sprayed it? Ever? The only foliar spray you may need is to cure chlorosis which is not life threatening to the tree, but foliar nutrients will not burn it. Look up chlorosis your tree does not have it.

Trimming and thinning branches is a lifelong job. They will have LOTS of dead branches that need to be trimmed OFTEN so you can get up in it to harvest fruit by hand without poking yourself in the eyes with dead branches. Carambola fruits don't do well with fruit pickers that I have tried.

Finally, the worst things that can happen to Carambola are drying out,
chlorosis, a hard scale (seemingly harmless to the tree) that gets on
the branches. Frankly they're hard to kill, I know I had a devil of a
time killing a Bell two years ago rather than bringing in a stumper.

About your custard apples, Are those new flushes? Anonnas get white fly (look under the leaves for them) and "maybe" scale but for the most part are also pretty disease resistant.

Bottom line is, I suspect something airborne is causing those spots on both trees.

OR it "could" be bacterial leaf spot. See:

https://www.planetnatural.com/pest-problem-solver/plant-disease/bacterial-leaf-spot/

thank you very much for your recommendation and tips, i have not sprayed the trees up to this point, i do not know if the landscaping guys are spraying something inadvertently. Somebody mentioned it could be anthracnose as well, i will try to spray it with neem oil and see how they respond.

possible it is anthracnose, or leaf spot.

and yeah, i agree with gnappi. its too small to let it fruit.

and i would lose those lower limbs. when the tree gets larger, it will produce a LOT of heavy fruit. and even limbs that are 2ft above the ground will bend down.

if you want to minimize the stress on the tree, cut 1 branch (lowest), wait a few weeks, then the next, but honestly, its a resilient little tree.

i see you have much which is a great thing, but its hard to see the base of the tree.

you shouldnt let the mulch go up aganst the trunk (if it is).

does it get good drainage ?

It actually looks healthier than mine, i wouldnt worry a ton about it.

post back if it starts getting worse.

thanks for your input greenman62

I will follow your advise in a few weeks, there is one fruit almost ready to eat, turning yellow already lol. As per the mulch i usually try to place it six inches away from the tree, i need to double check if it is covering the base of the tree. As per the leaf spots, i sprayed neem oil mixed with water yesterday late in the evening, when i woke up this morning i realized it had rained, hopefully the neem oil had time to dry on the leaves. i will buy liquid copper as well and try it in about a week, i read that should be a good combination to get rid of fungus, there is definitely something doing this to my plants, me sugar apple tree it starting to come out with new leaves and they are also getting these small brown spots, that one has flowers as well.

I will try to post more pictures later on today so you can take a look at it.

By the way, will the fruit be good to eat even if i sprayed it with the neem oil??

How is the tree now? I have something similar to what happened with yours.