SaaS to support mid-sized companies’ financial planning with real-time data and native collaboration isn’t the sexiest startup pitch under the sun but it’s one that’s swiftly netted Abacum a bunch of notable backers — including Creandum, which is leading a $7M seed round that’s being announced today. The rosters of existing investors also participating in the round are Y Combinator (Abacum was part of its latest batch), PROFounders, and K-Fund, along with angel investors such as Justin Kan (Atrium and Twitch co-founder and CEO); Maximilian Tayenthal (N26 co-founder and co-CEO…