You are way too picky. Not everything needs to be symmetrical. The square blocks interrupting the usual floor tiles are completely fine and that idea of design is often used; it looks fine. Also, your coin placement critique is completely unnecessary as it's completely fine throughout the level. Finally, windows and torches don't have to be at the same height and the same spacing (and neither do pillars) throughout the level.
I actually quite like this level and will review it when I get the chance.
For achieving to have a perfect level being picky is never wrong. We all want to improve don't we?
Yeah, not everything needs to be symmetrical but in some cases asymmetricity looks bad or wrong.
I just noted those tiles interrupting the floor tiles as a reason to compare it to a ruin more than a castle in reference to Cedrik's comment. I never said it didn't look fine. Though I said more about this on the chat than in the forum here or in the image.
The spacing between blocks, objects and coins should be perfect to match the player's movement though the level as seen in all official games and levels. Deviating from this would be uncommon or against common sense. As some of the coins are placed jumping perfectly might end up that the player lands on an object (followed by falling off eventually due to speed) or in front of it. Not quite what a player would like. Oh yeah and there are more reasons but w/e. Another reason is the aesthetic aspect.
They do not need the same height and the same spacing but if you do it on one part of the level you should keep the height pattern (relation between windows and torches). That's what I meant. If you don't it looks wacky. Oh and the spacing should just match the current position of the level it does not have to relate to the rest necessarily.
Besides all things I mentioned were rather suggestions on the aesthetic aspect in reference to level design of games sold tons of times with but not limited to Mario titles as well and it's still the op's decision whether to take my criticism by heart or ignore it as they do not see it fit. That's how all kinds of reviewing systems work. From level design review to code review.
On a side note: there's a historical reason why symmetry is important.