I often draw pictureillustrations.

You can also simply say, "I often draw." or "I often illustrate."

Recently, I've been wanting to draw fantasy-style pictureillustrations like in an old European style.

But, when I try to draw, I noticed (some signs of) fundamental cultural ignorance.

But I have never seen and worn old European style clothing, so it's hard for me to understand (it/them) deeply.

I'll collect a lot of data.

A more natural way to say this would be: "I'll research more on this matter." or simply "I'll do some more research."

Recently, I have been wanting to draw fantasy-style pictures, like old European ones.

"I have wanted" would also work here

But, when I try to draw, I noticed fundamental cultural ignoranceblindspots.

"ignorance" does work here but sounds maybe a little unnatural. A word like "blindspots" would fit here quite well, I feel.

I might be able to draw samurai roughly because I am Japanese and. I have also worn kimonos many times, so I understand their structure.

The original sentence gives an impression that wearing kimonos is part of the knowledge you need to draw Samurai, which I don't think is what you intended to imply. It's likely best to split this into two sentences that deal with each part separately.

But I have never seen andor worn old European style clothing, so it's hard for me to understand deeply.

This is a nitpick but, logically speaking, you should use "or" here. Saying you have "not done X or Y" means that you have done neither of them in any case. If you say you have "not done X and Y" then you may have done X or Y on their own, but not both together.
I wouldn't worry too much about this point since people will understand what you mean either way around, but I think a lot of English speakers would intuitively phrase it using "or".