Additionally for now, because TBOOT is not fully integrated into system boot, the admin needs to rebuild the Grub menu upon kernel update, or else no TBOOT entry will be present.
I think this needs to be automated and can be automated through the proposed 2 installed scripts.
However, since modifying /boot/grub2/grub.cfg is risky, it would be better (unless there is BLS integration) to have TBOOT create its own configuration file, e.g. /boot/grub2/tboot which will be re-generated during the kernel installation by the install script. /boot/grub2/grub.cfg snippet would just source that new file, similar to "custom.cfg" for example.

Please try the following after updating the kernel.

Please try the following:

# tbootentry=$(grep submenu /boot/grub2/grub.cfg | cut -d'"' -f2)

# echo $tbootentry  # <- make sure you got a valid 'tboot-<version>-<revision>'

# grub2-set-default "$tbootentry"
 
Or, if you only want tboot for the next reboot, and not as the default ...

# grub2-reboot "$tbootentry"

If the grub2-set-default solution is unacceptable, then use this ....

# LATEST_TBOOT_ENTRY="$(grep -w ^submenu /boot/grub2/grub.cfg | cut -d'"' -f2)"

# /usr/bin/grub2-editenv - set saved_entry="$LATEST_TBOOT_ENTRY"

This can't be fixed until bootloader supports multiboot and grubby and lists multiboot entries.

See bz #2107609
and bz #2107618

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