Good news. I’ve found a solution, my freepbx box is up and running 
.
If someone else ever gets to this point with his/her freepbx-distro raid1 box, maybe my way can help. What I did:
Regenerate initramfs with dracut and some options:
dracut --mdadmconf --fstab --add="dm dmraid mdraid" --add-drivers="raid1" --force /boot/initramfs-3.10.0-957.10.1.el7.x86_64.img 3.10.0-957.10.1.el7.x86_64 -M
Check if there is a file “grub” in /etc/default with the following content:
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed ‘s, release .*$,g’ /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT=“gfxterm”
GRUB_CMDLINE_LINUX=“rd.auto rd.auto=1 rd.luks=0 KEYBOARDTYPE=pc vconsole.keymap=us rd.locale.LANG=en_US.UTF-8 vconsole.font=latarcyrheb-sun16 crashkernel=auto rd.md.uuid=<UUID you’ve got out of mdadm --detail-dev-md2> rd.lvm=0 rd.md.uuid=<UUID you’ve got out of mdadm --detail-dev-md1> rd.dm=0 rhgb quiet biosdevname=0 net.ifnames=0 LANG=en_US.UTF-8”
GRUB_PRELOAD_MODULES=“mdraid1x”
GRUB_DISABLE_RECOVERY=“true”
GRUB_BACKGROUND=/boot/grub/splash.jpg
Then a
grub2-mkconfig -o /boot/grub2/grub.cfg
That was it.
Thanks for your attention :-).
Cheers, Pasco