Creating /forcefsck will not by default do anything in OSMC. For this to have any effect you would have to edit your /etc/fstab and change the 0 at the end of the line for the root file system for 1. Then touch /forcefsck would trigger systemd to do a filesystem scan.
However the recommended way to force a full fsck on boot in OSMC is to edit /boot/cmdline.txt and add the word forcefsck there.
This will trigger a full deep fsck scan and repair in the initramfs which runs very early during boot.
BTW, don’t worry about messages like Dirty bit is set. Fs was not properly unmounted and some data may be corrupt. for the FAT partition - this is fairly normal because we do not run an automated fsck of any kind for the fat partition - so after you have had even one unclean shutdown it will always say this.
If you want to you can change the 0 to a 1 on the end of the /etc/fstab line for the /boot partition which will cause it to be fsck’ed on boot, however this will slow your boot down by a few seconds.