Hi Lindsay,
Take a look at the attached spreadsheet. Looking at Monday, I've added in 2 new rows (rows 4 & 6) to covert the recorded opening and closing times to text using help from here in the Calculate column. I had to convert them to text, otherwise the Epoch version of the time would be filled in.
For the combined field, I've used this to concatenate the times:
if(${Monday}='Closed', 'Closed', if(${Monday}='All_Day', 'All Day', if(${Monday}='Set_Hours', ${Monday_Open_Text} + '-' + ${Monday_Closed_Text}, ${Monday_Open})))
Rows 4,6,11 and 13 are currently text but changing them to hidden the process should still work!
Carmel