IMO, your boss didn't do a great job of steel pickin'. One problem with 41xx steels for this part is that they lack nickel, which promotes deep hardenability. The severity of the quench necessary to avoid the pearlite nose on the TT plot is much higher than with a Cr-Ni-Mo steel like 4340, and that's not meant to imply that 4340 is a good die steel. All it means is that the likelihood of warpage is directly related to the severity of the quench.
Obviously you've got quite a chunk of money tied up in this part already, so saving it would be a good thing
For what you're doing, it sounds like you need hardness mainly for wear resistance and not necessarily for ultimate strength. I'd investigate the suitability of salt bath nitrocarburizing if it was my part. Its a form of surface hardening, but the temperatures are in line with those used for nitriding (around 1000*F or a bit less) and there is no severe quench. You end up with a surface that's in the low to mid 60's, and that surface has good lube retention properties which can be desirable in a process like you describe. If you do a search for Kolene, it should bring up some good info on the SBN process. Kolene is one of the owners of a proprietary SBN process, and they license it to heat treaters around the country. I've had it done to some parts in the past, and found it will do everything they say it will do.
I dont think you can get the 4130 hard enough to have any appreciable wear resistance without some type of surface hardness treatment. I've made a lot of cold flanging dies in the past from similarly heavy sections of 4140, and after a minimal temper they were seldom above Rc50-51. My guess is that your part will likely be under Rc50 after tempering. That's probably not nearly hard enough for resisting the wear that wants to happen when your Ti slides under high pressure during forming. SBN will give you a surface hardness and friction coefficient close to that of hard chrome, so it should do well for resisting wear. A treater who does the process should be able to look at your part and tell you whether there are certain features that would make the process unsuitable, such as thin highly loaded sections, etc. If it'll work, it should be about the safest process out there for getting the hardness with minimal danger of distortion.