- the leaves that were forming looked mostly healthy, some minor wind damage but not terrible. the dried tiny leaves looked to be at the end of a flush and i see that at the end of every growth cycle on my lychees.
- old hardened leaves in all the later pictures are browning. I suspect it is fertilizer burn or solute buildup. Were you flushing the soil regularly?
- what are those lack dots in the early pictures? i don't see them in the later pictures. i don't recall fungus being a major issue for lychees
In picture 4, the lychee is putting out some very nice new growths, which makes me think that it is getting enough water, it isn't too hot, and there is only mild wind. The old leaves getting burned like that looks like fertilizer burn. The tree also might have died back due to being repotted.
keep it watered, flush it out regularly. lychees don't mind wet feet, so adding a wick is optional.
also, do you have access to pine bark fines (or PB mulch?). I think you should consider making your own soil mix since it allow your plants to grow better (and its cheaper). You've got a lot of containers!