попробуйте с этим
str = ['published = 6/11/2019 at 8:02 AM']
published_date, time = str[0][11:].split('at')[0],str[0][11:].split('at')[1]
сверьтесь с этим Предполагая, что ваш mystr как указано ниже
my_str = [['\r\n ', '3/28/2019 at 8:52 PM.\r\n This list includes 36
eligible players.\r\n ', '\r\n \xa0\r\n '],['\r\n ', '3/28/2019 at 8:52 PM.\r\n This list includes 36 eligible players.\r\n']]
date = []
time = []
for x in my_str:
index_ = x[1].find('PM')
string_ = x[1][0:index_ + 2]
date.append(string_.split('at')[0])
time.append(string_.split('at')[1])
#op
print(date)
['3/28/2019 ', '3/28/2019 ']
print(time)
[' 8:52 PM', ' 8:52 PM']