Looks like you are having a lot of fun!
What kind of potting mix are you using? It looks like all peat or maybe coir. The medium may be holding too much moisture without perlite or sand, etc. to provide better draining mixture. It would contain no nutrients to feed them.
This may be why you are seeing issues now that they are growing true leaves and needing building blocks to grow with.
They would definitely need a little fertilizer, especially cukes and okra are heavy feeders. But if you are using peat, it may be too acidic for them as well.
This would be the time to figure things like this out,
Do you know when you will be able to plant them out? When is your last average frost? You may run into problems if your planting date is 2-3 weeks away. You may end up considering these "practice" but watching them grow and learning how they grow is an useful experience.