Kentmere will not tone anything like Forte. I hear a lot of talk about this paper and that paper.... but you aren't going to find an exact match.... The toning qualities of the Forte papers were one of their strongest assets. In particular their color and depth when matched with Nelsons gold toner. The kentmere papers I've tried are probably the least receptive to Nelsons.
Another strength was their price. Many people are suggesting Bergger papers. Bergger makes a fine product... so does Ilford for that matter. But neither look like Forte, and both are considerably pricier. (Warm tone fiber papers)
I'm hoping Photo Engineer will come up with a Forte-like formula one of these days.
I agree with you regarding the toning properties of Forte papers. It's likely that the present Adox, Foma, and (maybe) Slavich formulations are your best bet in terms of finding a paper that is responsive to toning. I haven't tried any of these three yet.
Incidentally, most (perhaps all...though Ole will disagree) Bergger papers were manufactured by Forte.