Fatawan,
It looks like it is a glue failure in the lamination of 2 wood pieces. I have never seen the CLSs up close to know if the wood outside the panel is 2 laminations.
In laminating wood for curves that is not unusual to have a glue failure. Some times glue application doesn't flow as it should.
A picture of the lamination and grain of the wood there would be more helpful.
If you can see that it is just separating on a glue line. Look to see if a faint line of glue holding 2 pieces of wood together extends beyond the separation in each direction. If it does ( which I am sure it will ) you just need to re-glue the joint.
The safest way will be to take the panel out of the frame. I'm sure people here can tell you how to do this. If you can remove the metal box that holds electronics do that. Turn the frame upside down. This will allow the glue to flow into the joint. Put some masking tape on the wood following the curve of the wood leaving the opening clear for glue to go into and squeeze out of the opening.
You will need a few small " C " type clamps. If you don't have any clamps they are inexpensive at a hardware or home improvement store. I would want to have 4 or 5. To many is always better than too few.
You will need a piece of 100 grit sand paper.
Once the speaker frame is turned upside down take a piece of sand paper and as best you can rough up the glue surface on both sides of the wood in the separation. Glue generally will not adhere to itself, so you need a mechanical bond with with the glue to each side.
After sanding, vacuum out any dust and pieces if any. Apply tape as previously mentioned.
With your clamps ready take come flexible wood or thick cardboard and cut some strips to protect the wood of the speaker from being damaged put the material on the wood and apply pressure with the clamps to see that the joint will close. If you are concerned about damaging the wood try it a few times with a little more pressure each time than check the wood to look for any inpressions from the clamp. Once you know you can close the joint you can continue with the repair.
You are now ready to apply the glue. Re gluing is always a crap shoot as sometimes glues don't bond to each other but I think you will be successful with this repair. I would use a polyurethane glue
( Gorilla Glue is the most known glue of this type and is sold in most hardware stores. Buy a small bottle as once opened it has a shelf life because moisture is what activates its setting.)
The instructions will tell you to moisten one side of the joint. A spray bottle with water will work fine. Just spray a little mist into the opening than squeeze a little glue in. Take a tooth pick and work the glue down into the opening and apply the clamps that you already know will close the joint.
If the handles of the clamps hit each other reverse every other clamp so they have as much clearance as possible.
This glue is good for this type of repair because it will expand and fill all voids in the joint. It will also ooze out of the joint as it expands over the next 3-4 hours so make sure if it dose everything is covered and will not get on the wood. Follow the cleanup instructions on the bottle and you will be fine.
Let it set for AT LEAST