I have ground off most the bamboo on a splintered back leaving just enough not to get into the old glue line and glued a new bamboo backing. Of course this requires a complete retillering and a poundage drop.
I suspect you could fill the void with superglue and fine sawdust and get by but I have never gone this route so am only guessing. That would be my first move, if this fix doesn't hold up you could always re-back the bow with new bamboo.
All the bows I re-backed with new bamboo were ones I made for other folk that popped a splinter on the back, because I always stood behind my bows I fixed them for them, all the bows I fixed many years ago are still shooting today.
Here are some pictures of my last replacement backing.
Grinding off the old bamboo, I use a belt sander.
![](https://i.imgur.com/8kUz9JG.jpg)
All the old bamboo removed to right above the glue line.
![](https://i.imgur.com/LaWNk1I.jpg)
New backing glued on in a reflex, removing the excess glue buggers.
![](https://i.imgur.com/xP98h7f.jpg)
This shows how much of the old bamboo I left.
![](https://i.imgur.com/2zNGcOM.jpg)
Done, this is Chad Weavers bow.
![](https://i.imgur.com/exiEEZp.jpg)
The handle already had the finish on it, this picture is before I applied finish to the rest of the bow.
![](https://i.imgur.com/u5iDlDg.jpg)
I ground off the old tip overlays while removing the bamboo and replaced them with new ones.
![](https://i.imgur.com/zZSuppC.jpg)