[The_Beast]

From what I understand, the heal amount added is based on cast times. Not sure if anything "hardcoded" is related to your issue.

This formula is found on the wiki here : http://wiki.eqemulator.org/p?Spells_HealModifiers

Item 'Heal Amount" - Amount specified on the item modified by formula below. (This value CAN critical)

    ​Value is modified by the 'total cast time' of the spell it is being applied to
    Total Cast Time is derived from adding which ever is greater(Recast OR Recovery time) to cast time.
    Total Cast Time (0 - 2.5 seconds). 
        ​Heal Amount = Heal Amount / 4
    Total Cast Time (2.6 - 7.0 seconds)
        Heal Amount = Heal Amount*(0.167*(Total Cast Time)/1000))
    Total Cast Time ( > 7.0 seconds)
        Heal Amount = Heal Amount / 7