Different Ccultures

Recently, I wanted to draw fantasy-style pictures like the old European masters.

But, when I tryied to draw, I noticed fundamental cultural ignorancerealised that I do not understand European cultural differences. .

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

Recently, I want to draw fantasy-style pictures like old European (pictures / ones).

European here reads as an adjective (as a noun, it would mean a person), so you need a noun to apply it to.

But, when I try to draw, I noticed a fundamental cultural ignorance.

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

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

If you had worn old european style clothing, that would pretty much imply that you have seen it, which would make "seen and worn" redundant. So it's better to say "seen or worn", I think.

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".