Horn speakers are really bright?

I think an all horn system set up right is impossible to beat. In cases like the Cornwall 1,2 and 3 the tweeter IS harsh and needs to be replaced with something like the LMAHLs or SMAHLs. Same for KLF series. There is also another possibility with those specific speakers which is crossovers that old have capacitors out of spec. Recapping can end a lot of sour sounds. None of the Klipsch speakers mentioned by the OP are purely horn loaded speakers so to say horn driven speakers like these infers they are an this is not correct.

I do have a pure horn loaded system. Klipsch K-402's with the latest K-1132 driver and new phase plug and a derivation of the MCM 1900 MWM bass bin except mine has a 108" throat and it goes effortlessly down to 27hz. Bi amped with Xilica for DSP and I have a stream of people who find excuses to visit me and listen. Stunning accurate realism at low or high volumes and if you want to play for sound effects fireworks can be felt across the room at higher volumes. The problem with good bass horns is the required size to get good clean low end hz and most people do not want that big ugly WAF zero in their house.

 Good all horn systems are relatively rare because they are harder to do than regular speakers. I think most audio types have never heard a good set and base their all horns suck on so so or worse sets. DIY forum has a ton of information on all horn systems and many blueprints and knock down kits to give you what you want but you have to get your hands dirty in many cases.

The true pleasurable lovable sound from what ever speaker design the individual chooses from I hope you choose what sounds near perfect to you. Not others. I personally have four  different sets of horn speakers and two regular design speakers. Tweeters -( paper or dome ). I simply love the sound of each of my individual speakers. One design is not written in stone for me. I understand some style of music ( classic rock funk blues jazz and r&b ) will sound better on different  style of design  speakers and I am very much so appreciative of that. So I am willing  to compromise to get the absolutely best sound to my ears. 

Horn speakers especially high frequency horns can sound sharp or brightr or screechy or whatever but properly done will do trhings that the ubiquitous dome tweeter simply can't. Mounted on a waveguide and using severe toe-in provides a very wide sweet spot, about as wide as the speakers are apart. Also the wavegude when positined as mentioned prevents or limits the damage strong early reflections cause. Hard to go back to domes after hearing a good horn/waveguide setup.

Pink Floyd never played through dome tweeters!  😈

I just got a pair of klipsch kg4s this week and they don't sound harsh or "shouty" to me. On the contrary they (to my ears) sweeten rock music of the 60s and 70s. I've been listning to them for hours all week with enjoyment. Do they reproduce sound to RIAA standards? Not even close. But if you want to crank some alice cooper they are really fun. The horns add a clarity to vocals and guitars that just can't be beat for $250.

I wonder how much of your experience is the speaker position next to all that equipment tv screen and so on. The normal horn dispersion is getting reflected by the walls and equipment including the tv most probably.

I have a different category of horns, hand turned American maple and a super tweeter set up powered by Luxman M900u, etc. my experience is based on at least a four foot clearance around the horns. A better layout here could improve your experience I’m thinking if you can drop to two shelves or reconsider the locations and set ups. Watching Acoustic Fields Dennis Foley offers loads of information.

That said my horns have never been bright or harsh. Only using an Esoteric K03Xs did I find it too harsh not even on horns and sold that unit. No regrets.

You’ve got two great sets of equipment that might even give you greater pleasure and experience if you can experiment a little. Others comments on certain equipment and synergy factor here too. Room acoustics and speaker positions are a strong part of that mix.