Florida regulations require operable windows in rental properties.
Having working windows can be especially enjoyable during the cooler winter months in Florida.
When renting a house or condo, you should insist that all windows are fully operable before moving in. If the windows do not open or stay open properly, the landlord can contact a local professional company to replace the window balance springs and restore proper operation.
A half-circle window is not cut with a regular knife. It is mainly a special-order item.
You can always install temporary plexiglass and use different cutting methods as a short-term solution.
In Pembroke Pines, Florida, there is no factory that fabricates this type of window on demand, but you can find local suppliers that sell plexiglass to use temporarily while you wait for the permanent window to be ordered and fabricated.
https://sliding-glass-door-repair.com/pembroke-pines/window-repair
Also here is a local plexiglass source: http://pembrokepines.businesslistus.com/specific/Polymethyl-methacrylate-resins,-plexiglass.htm