Help, my system seem to have slowly gotten " bright"

I am glad it is not a hearing issue.  Now, to diagnose the problem.  Put on something that is a mono recording which exhibits the problem.  Use a balance control, or disconnect one speaker to listem to one channel at a time.  Is the problem the same for both channels?  If there is a difference, try switching the left and right cables to the speakers.  If the problem stays the same, it is the speakers that are at fault.  If it switches channels, it is something upstream of the speakers.  You can move progressivel upstream doing this kind of switching to isolate which component is at fault.  If you have problems in both channels that is about the same, it would be an odd sort of failure, particularly if it is the speakers at fault—it would mean identical damage that is short of taking out the tweeters entirely.

The fact that you’ve had multiple tweeter failures suggest that you are over driving your speakers or that something like your amp is defective and maybe sending a lot of ultrasonic energy to the tweeter and damaging it.

I’m assuming you’re noticing brightness on the recordings you have played before and are familiar with. 
So the question is…did anything change in your room? Furniture updates or moving things around? Removing or changing area rug? Removed window treatments? Any changes in wall decor such as paintings, etc.? Changes in power delivery such as adding or removing power conditioner, changing outlets, running dedicated lines?

I have isolated each speaker and they both some the same. The room hasn’t changed. I am very aware how the placement can have an effect on the sound. I can change the bass sound significantly by just moving them closer to the wall. As I mentioned I have  2 sets of speakers. I have some revel f208’s that are like 7 years old. I later got some revel f228be with is basically the same cabinets with better drivers. I have loved since I got them, they do have a similar sound to the f208’s but just better all around.

So I have just moved the 228,s out and put the 208,s back in and do not hear the excessive brightness present in the others. So I am not sure what to do now.

I did a tone test but couldn’t really notice anything odd.

So, either the tweeters are damaged (but still work ) or the crossover got damaged somehow. Are either of these possable especially the crossover ? What would a marginal crossover sound like ?

Since one of your speaker pair sounds good, you have a good setup for debugging this.

My recommendation is to try the different frequency sweep (you can easily find this on Tidal/Qobuz/etc.) and for each frequency write down spl at your listening position.  Do this for both pairs of speakers and see if any significant difference pops up.  If you don't have a SPL meter you can use a free app for your android or ios phone.