Arcane Familiar is called when the buff already exists.

I had the same issue.

The file is missing the check for the buff.
You need to add the spell ID for the buff:

ArcaneFamiliarBuff = Spell(210126),

Then for the code to summon the familiar it becomes:

-- summon_arcane_familiar
if S.SummonArcaneFamiliar:IsCastableP() and (Player:BuffDownP(S.ArcaneFamiliarBuff)) then
  if HR.Cast(S.SummonArcaneFamiliar) then return ""; end
end

Fixed in 2ce2baa.