Fighters
They could be; but its fun to try and work out a logical progression of design families. Most real-world designs build on ones that have gone before so its not entirely outrageous to try to look for links. Unfortunately, if we go by appearances, the closest resemblance to a Gratha is the USAF B-1 bomber.
Assuming that Gratha did evolve into Jalkehi what are the steps and why? The original Gratha armament is two lasers and two mass drivers. Now, the problem here would be that the two guns have different ranges reducing firepower concentration (arguably, the Kilrathi also like to fire at longer ranges, hence their concentration on lasers in WC1) . So a Gratha Upgrade may look at giving the pilots what they want - ie increased long-range firepower. To do that, the designers might well replace the two mass drivers with a pair of lasers - but while that gives four long-range guns, the loss in total firepower is worrying. So the designers add a belly-mounted particle cannon (also long range) and we have the Product-Improved Gratha armament. So thats phase One (PIG-1).
Now, Confed Fighters have a field day by sitting behind the clumsy Kilrathi heavy fighters and chewing them apart. Thats one reason for a tail turret. The other is the arrival of torpedoes - turrets are necessray for self-defense while doing a torpedo attack. So the PIG-1 Gratha needs a tail turret. The problem is the engines are in the tail position. So the existing pair of large engines are replaced by a cluster of outboard smaller ones (of same total thrust) with the cleared space between housing the turret, Thats Phase 2 (Gratha PIG-2).
Now if we look at the result, we've added a lot of weight aft which is going to shift the cg aft, making the craft difficult to control. So to shift the cg forward we reverse the sweep-back of the wings to forward-sweep, that shifts the cg back again. Add a pair of canards forward and we're there. Thats Product-Improved Gratha phase three (PIG-3). At that point so little is left of the original design, it gets a new name, Jalkehi.
Now there is some slight evidence for the PIG-2 stage in that one of the books mentions a torpedo fighter called the Graxa. That could conform to PIG-2. False Colors mentions the Gratha as a forward C4I ship (basically an equivalent of the real-world E-2C) and that is real hard to square with WC1. I don't like Forstchen as an author anyway (I find his constant harping on the idiotic brainless Confed government irritating).