@fleckintosh and @Ario: The result is awesome! Thanks a lot!
I compared these film simulations with the C1 Extended Filmstyle Set. The result is much more subtle and much better aligned to the JPEGs straight from the camera. I definitively recommend using these styles, not the ones from C1.
The procedure is a bit complex, so let me summarize for all the newcomers. The result will be, that these great Fuji film simulations provided by fleckinthosh are saved as C1 ICC profiles, specific for your camera (X-T1, X-Pro2, X-T2) and can be used regulary in C1 under Basic Characteristics without any hassles:
1) Download the ICC files from Dropbox-Download, either for X-T1 or X-Pro2 (look at the end of the file name for X-Pro2). I used the X-Pro2 files for my X-T2, because the X-T2 has the same sensor as the X-Pro2. So far, all works fine.
2) Copy the downloaded files to the correct C1 directory. The directory locations are:
On a Mac system the custom ICC profile will be located in: Users/UserX/Library/Colorsync/Profiles
On a Windows system the profiles will be located in: Users/UserX/AppData/CaptureOne/Color Profiles
3) Start C1, select a picture taken with the camera you want to save the film simulation for (i.e. X-T1, X-Pro2 or X-T2, depending on the files you downloaded)
4) Apply the desired profile to this picture (taken with the selected camera, i.e. X-T1, X-Pro2 or X-T2), by selecting this profile from Base Characteristics/ICC Profiles/Fuji/XT-1 (the tool Base Characteristics is in the Color Tool Tab)
5) Open the Advanced Color Editor
6) Save settings as ICC profile giving a useful name (the correct camera name is already there). I did use a naming as "FujiXT2-C_1.Provia", where "C" stands for "color", and "FujiXT2-B_1.Acros", with "B" for Black & White. With the numbering, all appears later in a nice order
7) Close C1, go to the Color Profiles directory and delete the temporary files (the ones downloaded)
8) Start C1 again, go to the Color Tool Tab and Base Characteristics, then choose under ICC Profiles the option only display recommended. Then only the ICC profiles matching the camera used will be shown and the list of ICC profiles becomes much shorter and better in overview
From then on, you can select the Fuji film style from Base Characteristic/ICC Profiles and the result is already shown in the picture, when the cursor is located over the style name. Because I do that very first, I have added the tool Base Characteristics in the Lens Correction Tool Tab, then I apply lens correction and film simulation in one go.