Strange old versions of Frei0r effects kept popping up in my script compiled Kdenlive, although the script compiles Frei0r every time anew.

So I had to change a couple of lines in the start_kdenlive script:

line 26 to:
export LD_LIBRARY_PATH=$INSTALL_DIR/lib:$INSTALL_DIR/lib64/frei0r-1:$LD_LIBRARY_PATH

Note1: here I only changed /lib to /lib64

and line 39 to

export FREI0R_PATH=$INSTALL_DIR/lib64/frei0r-1/

Note2: I cut away all the /usr paths

Note3: on a 32 bit system it will probably be /lib instead od /lib64