I think the intended grouping of that sentence is (((Stripe founders) are (youngest Irish billionaires)) (with funding)), i.e. they're simply the youngest Irish billionaires, not the youngest Irish billionaires with funding. Still a fairly narrow superlative, but less ridiculous than the original interpretation. "Youngest Irish billionaires" is the lede, "with funding" is the actual news story - they're announcing Stripe's funding round.
I don't think the "with Funding" is really meant to narrow the selection. I think it means something more like "based on the valuation from new Funding, are Youngest Irish Billionaires"
