After reading through this whole thread again, I have decided that I will probably try the workaround of placing a little insulation tape where the sharp edge meets the cable to prevent further damage and add some kind of foam/silicon/filler-material on top of the connector. Despite the symptoms being different after the software update, I can see a clear correlation between frequency and location of appearence of unresponsive display areas I have to deal with now and the erratic touchscreen inputs from before. If that doesn’t help I might also have to go down the road of replacing the screen/phone, but I’m hoping for the best. 
I’m currently still on the lookout for the proper material though.
@Hans_de_Vries is your workaround still holding up? Your last update has been a while ago, but you seem to have made some good long-term experiences with the tightening of the connection.
Thank you for the Amazon links @Delan and @twoexem! I’m actually considering buying the packet suggested by @Delan - if your solution still works for you. Did you stick with the 0.5mm variant or were you forced to ‘upgrade’ to the 1mm version at some point? There seem to be several people suggesting that the connector has to be pushed down quite tightly, so I’m wondering wether 0.5mm are enough. Also, if you have ever opened your device since than, did you notice any flattening/degradation of the material similar to that described by @nureac?
Speaking of @nureac’s solution: Did the expandable stuff work out for you? What product did you use (I’m not familiar with that stuff) and is that even safe for electronic parts with regards to static electricity?
(Sorry for asking so many follow-up questions at once. I’m just trying to process the useful information from those >500 posts and figure out the best way to go before jumping into action with regards to hardware modifications.)
Also thanks to @Zorugal for suggesting that screw-glue stuff (Loctite). Is there anything I have to be careful about when applying that stuff? Can that interfere with future repairing attempts or is it easily removable/cleanable?
As for the Sharp-Edge-Theory devised by @guits: I’m also a bit wary of sanding down the edge due to aluminium dust as mentioned by @facetto. Is there a reasonable way to keep that process clean? Also would that modification void any potential warranty claims regarding the Ghost-Input issue? I guess some electrical tape at the correct position will do. Do you think it’s better to place it over the edge, on the cable or both?
Speaking of which: I noticed that @facetto wrote something about simply using Tesa film. I’m pretty sure that’s not advisable due to static electricity. There’s a reason all of those antistatic materials exist in the context of electronic devices.
But enough with follow-up questions. Just a few more remarks:
I totally agree with @guits that the question ‘What caused the Ghost Touches’ posed by @Chucrute in response to the software update message should be answered by the FairPhone Team (soon). Transparency about issues is a must for a device that aims to be repairable. Knowing the outcome of FP’s investigation would really help us in deciding which modifications are best made to resolve those issues and ultimately get around the whole process of relying on FP’s support infrastructure for repairs (which would be a win-win for both parties in my eyes, as it saves cost in many ways). I really hope that they won’t keep this under the wraps for simple short-term PR-reasons…
Finally I don’t really think that marking @anon1128606’s mention of the update as the final solution for this thread is the right choice. (Maybe I also just misunderstood what “solution” is supposed to mean in this context, as I’m rather new to this forum.) The problem apparently still persists with various symptoms for many, and the software update is a nice effort in providing a workaround that doesn’t really solve the issue. Having read all of the discussion here, I wouldn’t treat the post-update issues as a separate thing from the original problem, as the underlying cause remains the same.
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