Oh that is such a bummer! I have an old oblique that I don't mind messing around with the flange on. I use that to try different nibs. You can adjust your flange on your Curv-E to fit any nib but once you start changing it around, it does make it less easy to manipulate. You can email Edward to see if he has any tips for making it fit.
Honey, I ain't messing around with my Curv-E; nope, nadda, not. I will leave it as is for my now second-choice Leonardt Principle EF's and whatever else size it fits.
Back in the day, they didn't make flanges to fit any specific nib. We just used a little plier to adjust it for whatever we were using. Although I did have one pen that had a little screw in the flange which made it a bit easier.
I saw a nice Russian made holder yesterday with adjustable flange ($40). Not gorgeous and all like my CE, but it works for what it is supposed to do, right? Perhaps as funds come to me I "may" purchase. Meanwhile, My Hunt 22 is doing fine in a straight holder. Not sure why/how I got hung up on obliques anyway. I am thinking when I first starting reading up on calligraphy that was what I saw most [shoulder shrug]. I do not believe (especially using guidelines) that my slant is suffering for using a straight vs. oblique; so there I have it. It is a matter of keeping on practicing and learning. Plus, that hole pascribe "thing" about supposing to use straight anyway.