Vague damage multiplier text

I wish they would differentiate whether +50% meant adding it to the base damage (65% attack becomes 115%) or multiplying the entire attack by 1.5. If we're deckbuilding and theorycrafting these differences are important to get the maximum damage. For characters like rin we need more base damage and for characters like Haru it would be nice to know which buffs are multiplicative which matters more for her than her base damage.

Some examples I can think of that I confirmed:

Weaken status: damage x .75

Morale: +20% to base dmg

Fortitude: -20% to base dmg

Mika source of water: heal x 1.5

Mika tactical analysis: +50% to base heal

Veronica reload: damage x (1.0 +0.5x)

Rin Drawing slash: damage x 1.5

Am trying to make a spreadsheet and test more cards but it's a lot of dam work.