5 axis tool offset

I believe there is a 5 axis configuration...

There are several.
So what exactly do you mean by 'xyzab'? That can mean a few different kinematics.

For this geometry there is this sim config in the current development branch:
github.com/LinuxCNC/linuxcnc/tree/master...ndle-rotary-nutating
I would suggest you have look at that before you start looking at changing over from trivkins.

You should also be able to install the kinematics component on version 2.9 using 'halcompile' (for which you may need to install the linuxcnc-dev package). The component can also be found here:
github.com/Sigma1912/LinuxCNC_Demo_Confi...ary/xyzacb-snrtr_twp

For your case, you would set the nutation angle to 90° and ignore the C axis. TCP will work just fine but the TWP feature will currently only work for the head rotation.

TWP is the 'tilted work plane' feature, you are likely after the TCP mode that keeps tool tip position stationary when the tool orientation and offsets change.
If your CAM is capable of handling tool offsets then you can keep using trivkins.

Removed your last post. You cannot just past images into the post like that you need to use the Attachment box.

I'm not sure what you mean but I'm also not a 5axis expert so somebody else might be able to say more.

5 axis is certainly a bit off the beaten track. You might want to try on the linuxcnc discord server or on a forum that caters more to 5axis machining and CAM applications. I'm afraid I don't have any links for you though.