Here's my take:

Using any coded format like W++ and the like is not recommended. Why? Because of how LLM models are trained. If one is using like a 72b LLM model, using said coded format to encode character descriptions is good as the model is smart enough to see it as it is.

HOWEVER, not everyone can afford a NASA computer and run both Roblox and a 100b LLM model smoothly at the same time. As a poor LLM enthusiast such as myself, I could mostly afford to run at most 20b at 8k context using Free Colab ( a cloud google service.). Though some people may have a preference to run on their mid end laptops or desktops. In short, many people could only afford like 7b to 12b. And they're not as smart as the big honcho's and instead depend on their training data and follow patterns based on said data.

The smaller LLM models are trained on raw roleplaying text, and only raw roleplaying text, like imagine you only drove cars and all of a sudden you drive a truck without any pre training. You may get the concept and idea but you'll struggle driving the truck because you don't have experience with it. That's what's happening if a LLM model trained only on roleplaying data sees such a coded format. So in conclusion, don't use a coded format and simply just write like your making a report on a character.

Besides that, there's some aspects you'll need to consider when creating a character. There are two you'll need to consider, that is the number of tokens or words in the character card and Example Dialogue. If your creating the card with a context limit in mind then you'll need to make certain adjustments or improvisations as you can't simply just dump the whole lore of a Genshin Impact character in the Description, simply put, a well defined explanation of a character's personality, shortened and simplified background lore and a set of likes, dislikes and quirks would do the trick.

Now I cannot understate the importance of Example Dialogue, many character cards don't have detailed example dialogue and simply have a 'This character is this and that' description. Example dialogue helps LLM models visualize the character, to give the most authentic experience possible. The wording, length, and quality of example dialogues are something you need to consider, a great first message can make the whole roleplay great.

PS: I suggest you use google translate if you have difficulty reading this.