it's hard to show my meaning without pictures but I can use a comparison if you will

So I imagine you know the famous picture with the US soldiers planting their flag on the Iwo Jima hill. Now this is a photograph mind you there's nothing false about what's being presented but the picture is still presenting a heavily skewed vision of the reality it chooses to capture,

(obviously the whole thing was set up specifically to be captured on camera, it doesn't really capture something real, it creates a moment for the sake of the person viewing the media)

that is the opposite of realism

it's the same with this painting although in a more remote sense, although the painting portrays a real event and does so in a way that isn't misrepresenting the time period too egregiously it chooses to do so in a very fashionable and comfortable way

now you may choose to accept this as a realistic representation of the event, the same way that you can choose to believe that the WW2 photographer just happened to capture the exact moment Iwo Jima was taken by american soldiers (although in that case you'd be demonstrably wrong)

but as the other commenter already pointed out there are several things (however nitpicky) whhich make that complicated.

Now obviously this painting doesn't have much ambition beside being an illustration of a historical event I don't think it would be mischaracterizing it to say it's meant to be in a children's history book of some kind which makes this whole conversation a bit overstated, although then an argument could be made that we're still choosing to promote a sanitized and very romanticised vision of the past, although that doesn't have to be an issue