I have two objections to this, although I'm not the biggest fan of cooking manga (I don't really seek it out), first about unknown taste and second about mixed taste. Both are kind of interconnected.

This unexpectedly ended being kind of a large answer.

So for unknown taste, I might not know how a dragon tastes, BUT, I also don't know how a turtle tastes. But I can enjoy reading a cooking manga where they cook a turtle into a soup and I even kind lf imagine how it tastes like. There are also many descriptors yhat are vaguely useful, like sour, tender, etc that coupled with the image hives a rough idea regardless of how wrong it may be in actuality.

Second is when they make their fantasy ingredients contradtable to IRL ones or a mixture of other two ingredients. It is the same as when people tell me frogs taste kind of like Chicken, if you told me a dragon had stiff meat due yo all the muscle and that it tasted kind of like a hard bird meat, I would completely believe it and wouldn't detract , now if it says it tasted like a gorilla we come back to completely unknown flavours and imagination has to do some heavy lifting.

At the end if the day I think we can appreciate some of the beauty in fantasy food, taking heavy inspiration on IRL dishes but with twists that sound delishious.

While making this point I was constantly thinking about dungeon meshi and toriko, the first utilizes fantasy tropes appropriately to subvert your expectations and make unexpected but reasonable flavours out of fantasy beasts (also dome of the cooking methos are hilarious, like for the trap chest at the beginning). Then you have Toriko which used a lot of fantasy fruits that are mixed of what we have, like it's not that difficult to imagine what a caramel melon would taste like.

At the end of the day, I don't think fantasy cooking is that much worse, but the authors do need a lot more creativity to pull it off.

To finish, here is an analogy, It's kind of like fixtional sports manga (although not 1 to 1) most people wouldn't seek out reqding sport manga based on rules that were though by the author but that no one had ever played, those sports tend to have inconsistencies on rules, sometimes they aren't fun to watch, they can be unintuitive, etc. Those are inherent problems that these works face that normal sports manga don't because of the simple fact that sports have been developed across many years by a lot of people into something people enjoy, also the familiarity is an aspect that boosts enjoyment. But those being inherent problems doesn't mean fictional sports in media are bad. They do require a lot of creativity and thought, especially if the author is gonna focus on them or else you get a shitty sports like quidditch.

PD: love that more manga discussions are creeping into the community, I lowkey hate [DISC] posts being so frequent, although I fo understand the necessity to keep things alive, but most people aren't keeping up with more than a few manga and that makes it so there isn't much discussion to be had unless the community grows to a large enough point that you have people reading everything.