import re
text_list = [' something\npatternx: text_i_want One Department',' something patternx: text_i_want One foreign Department',' something\n patternx: text_i_want Two office']
text_list = ' '.join(map(str, text_list))
rx = r'\bsomething\s+patternx:(.*?)\b(?:One\s+(?:Department|foreign(?:\s+Department)?)|Two\s+office)\b'
print(re.findall(rx, text_list, re.DOTALL))
# => [' text_i_want ', ' text_i_want ', ' text_i_want ']