as the title says is there any harm to putting the Xgimi H2 projector up side down?
placing the projector as normal makes the picture show on roof, and manual keystone does not help.
All you have to do is read the placement and ventilation recommendations in the manual. For Most projectors it’s recommended that you leave space above the projector for heat dissipation. Although I assume this applies for upside down projectors, I think it’s ok to leave it as you did, because there’s plenty of space for heat be released from the projector all around it.