If anyone could, please...

you can use UnitStat("player", 4)*GetCombatRatingBonus(CR_VERSATILITY_DAMAGE_DONE)*GetCombatRatingBonus(CR_CRIT_SPELL)

Those functions already exist. Not sure if they still work but they're there.
EDIT: Oh, but you do have to specify things like weapon damage or attack/spell power for each spell as SpellInfo() for the ability.

Alternatively you can make your own custom functions within the script to do the same thing if the built in ones are broken. I did that on my Feral script.

Example:

AddFunction DamageAfterArmor asvalue=1
{
    
    if target.DebuffPresent(rip_debuff) 0.7282
    0.6802
}

# Damage in thousands
AddFunction FerociousBiteDamage asvalue=1
{
    PersistentMultiplier(ferocious_bite) * { 1 + MeleeCritChance() * 0.013 } * AttackPower() * 0.00749 * DamageAfterArmor()
}

For healing spells I'm sure it'd just be SpellCritChance() and SpellPower() and you wouldn't have to worry about armor.