Samsung S4 Mini (GT-I9195) TWRP recovery fails

I have a Samsung Galaxy S4 Mini (GT-I9195) and successfully installed CyanogenMod 13 with the CM 13 Recovery on it. Now I am stuck with the installation of GApps by means of TWRP. I have tried to follow this tutorial to install TWRP (3.0.1 or 2.8.7): 1) App Install Method: it tells me that something went wrong and it does not boot the recovery, indeed. What seems wired to me is that when I have to choose an image it shows me the device code **serranolteusc** and **serranoveltexx** for my S4 Mini rather than **serranoltexx**, like on the website of CM 13. Is this normal? (I even tried Flashify instead of the TWRP manager, but it did not function!) 2) Since I am on Linux and have no Windows, I cannot use the Odin method. But I tried Heimdall via heimdall flash --RECOVERY twrp.img --no-reboot to no avail. 3) I tried the dd Install Method via dd if=/sdcard/twrp.img of=/dev/block/platform/msm_sdcc.1/by-name/recovery, but it still does not boot into recovery mode. Is it possible that there is an issue with the path in of=/dev/block/platform/msm_sdcc.1/by-name/recovery? Is it possible that there is no TWRP for **serranoltexx** available?