Final solution would look like this:
concat(
if(min(${reporting_date_month}) = 1,
"January",
if(min(${reporting_date_month}) = 2,
"February",
if(min(${reporting_date_month}) = 3,
"March",
if(min(${reporting_date_month}) = 4,
"April",
if(min(${reporting_date_month}) = 5,
"May",
if(min(${reporting_date_month}) = 6,
"June",
if(min(${reporting_date_month}) = 7,
"July",
if(min(${reporting_date_month}) = 8,
"August",
if(min(${reporting_date_month}) = 9,
"September",
if(min(${reporting_date_month}) = 10,
"October",
if(min(${reporting_date_month}) = 11,
"November",
"December"
)
)
)
)
)
)
)
)
)
)
),
" through",
if(max(${reporting_date_month}) = 1,
"January",
if(max(${reporting_date_month}) = 2,
"February",
if(max(${reporting_date_month}) = 3,
"March",
if(max(${reporting_date_month}) = 4,
"April",
if(max(${reporting_date_month}) = 5,
"May",
if(max(${reporting_date_month}) = 6,
"June",
if(max(${reporting_date_month}) = 7,
"July",
if(max(${reporting_date_month}) = 8,
"August",
if(max(${reporting_date_month}) = 9,
"September",
if(max(${reporting_date_month}) = 10,
"October",
if(max(${reporting_date_month}) = 11,
"November",
"December"
)
)
)
)
)
)
)
)
)
)
)
)