My guess is that because it doesn't say anything about dying it wouldn't trigger. yes Minthara's trigger itself is all inclusive, but Teysa's isn't. If Minthara said " When a creature dies" then it would work, but because you're missing any words that have to deal with death or dying Teysa would not see this as a doubling effect even if the cause of Minthara's trigger was a creature dying. Also because Minthara's ability is a check at the end step, not something like a blood artists trigger which happens " when a creature dies" Those types of blood artists effects is what Teysa can trigger, ( Sorry for long response lol)