Alright then, second floor. There's a staircase outside in pretty plain view, which gives us a good basis for scaling. It looks to me like there's 18 steps there, but since some are concealed by a pillar we'll call it 20. The US standard step goes by the 7-11 rule, meaning an average of seven inches high and an eleven inch tread (More specifically, the tread is to be ten inches at an absolute minimum, and the rise is to be seven and three-quarter inches at maximum). We'll round that up to eight inches, in the interest of leveraging the math against me.
Twenty steps, eight inches apiece, puts the cabin's second level deck thirteen and one third feet off the ground. Assuming the ground level deck is somewhat elevated from the dirt, we'll call that thirteen and a half feet, or 162 inches. The present day average height of a seventeen year old Japanese girl is 158 cm, exactly five feet two inches. To adjust for Emi's age, we'll knock that down to five feet even (152.4 cm). The average arm length of a human female in the 150-155 cm height range is 30.75 cm, giving Emi an overall standing reaching height of just over six feet. For women, a vertical leap in the 16-20 inch range is considered above average. So, without pushing her body hard enough to fuck it up, Emi's vertical leap should get her hand up to ~7.34 feet.
Leveraging a self-healing quirk to get an extra six feet or so at most out of the jump, grab the edge of the deck, vault over the railing while her legs healed, and flinging herself through a window that looks like it should be able to accommodate a teenage girl doesn't seem particularly egregious for a setting where Eraserhead is a trained but unenhanced human. Given the height of the window, even if they'd been looking through it instead of distracted by each other, the catgirl and cokefiend would have been very unlikely to see any of the leadup before Emi is heading straight for the window, meaning Daze's initial reaction would be a perfectly reasonable reaction IC. My IC post has been edited to include such detail, but given that the two inside wouldn't have seen it either way...