Good day, Mr. Joulupukki.
After re-reading the entire thread, I have pose a few questions and observations, which may be way off base as I am still a rookie at some of this ... but here goes anyway:
* Why not ground Pin 1 at the mixer end of the cable, connecting it to mixer chassis? I believe you connected Pin 1 to the XLR shell at the mic end, but not at the mixer and (I believe) not at BOTH ends of the cable. I have solved similar RF issues in amateur radio mic cables by connecting Pin 1 and shell (and, ipso facto, with the transceiver chassis.) While this may not be the most recommended practice, it has solved similar problems, and, to coin a phrase, I favor "experience over form."
* Speaking of ferrite beads, perhaps you could take a cue from the amateur radio playbook by installing one or more clamp-on ferrite beads on your microphone cable, forming a simple RF choke. I am encouraged you can tame the problem by modifying the cable using the Neutrik EMC connectors. You get more bang for your buck if you can loop the cable through the toroid multiple times. Looping the cable through a single toroid provides substantially more choking impedance than adding a second bead. You might consider FairRite Mix 31 for HF frequencies, Mix 43 for UHF, and possibly Mix 61 or 63 for UHF frequencies. Search for articles on this type of choke and Pin 1 problems by Jim Brown, K8YC, on the Internet - he has several articles that measure the choking effect of various configurations and mix types, especially in connection with microphones and audio gear.
* Wild Alex Guess No. 20838 - Occasionally, a LONGER wire works as well as a shorter wire when a lead is acting as an antenna. Perhaps slightly longer twisted wires inside the mic body would get the click. Doing this solved a problem with my underground sprinkler system when 40 meter QRO transmissions activated just one of the sprinkler heads. Adding wire decoupled the system at the problematic frequency. Occasionally, it is merely a matter of avoiding resonance (including avoiding harmonic frequencies) and a longer wire may work as well as a shorter one to decouple the offending device. Sounds silly, but I believe experience triumphs over theory.
* I am unsure whether you determined whether the problem is limited to your particular cell phone, or or is endemic to the entire species. If limited to your phone, the solution may entail modifying the phone instead of the mic. (Of course I am reaching a bit on this aspect, but there is no harm asking ... I hope.)
* How did you determine the capsule, itself, is not the problem? Does the problem occur with the original capsule? Does it occur with the original board? I apologize if I missed previous mention hereof.
* For what it is worth, I second the motion to upgrade the cable to one with better shielding, especially in conjunction with the Neutrik EMC connectors and/or add-on ferrite beads.
Just a few observations and serving suggestions from one who has solved similar RF interference issues in similar situations. / James