It looks like most of the seeds germinated. Unfortunately, again most of the sprouts died shortly after germination while still under an inch tall. The pulasan seedlings I got in the spring did the same. Not sure if this is a soapberry thing, lychees seem to have a much higher survival rate
Anyway I got two healthy plants out of this batch so far, and possible more will survive given time. I am curious what others' experience with rambutan is. Every one of the seedlings from my previous batch that survived seems to have yellowing leaves that go necrotic quickly, though so far they have been replaced by new leaves. I tried acid soil, high potassium fert, high humidity. Not sure what it is they are wanting.
I grew some rambutans from grocery store fruit last year. Apparently, the fruit was not irradiated. But, since I had never had any success when I had tried to germinate rambutan seeds in previous years (probably because that fruit was from a different company and had likely been irradiated), I did not try and germinate those rambutan seeds. I just threw them into a compost bucket. In less than a month, I had a dozen or so rambutans. They grew excellently for about three months until summer ended and fall started settling in. I could not bring in my compost bucket for the winter; it is filled with insects and other things I do not want indoors. But, transplanting those rambutans killed them almost instantly. They were all dead within a couple of weeks. Although I had tried to take care not to disturb them too much during transplanting, I had apparently still disturbed their roots too much.
So, if I were to try and grow rambutans again, I would put them in an extremely rich potting medium: basically put the seeds in pure compost. I would keep them in part shade. The environment would be one matching an Alabama summer: very hot and very humid. Compost readily retains moisture; I do not remember watering them much since I think it rained every few days, but I would water them as needed.
Maybe try some of those tips and see if they work for you.