import re
pat = re.compile(r'(?:Wohnfläche|Wohnfl|Wfl)\s*(\d{1,3}(?:[.,]\d{1,2})?)\s?m\s?(qm|m\u00B2)|(\d{1,3}(?:[.,]\d{1,2})?)\s?m\s?(qm|m\u00B2)\s*(?:Wohnfläche|Wohnfl|Wfl)')
strs = ["12,56m qm Wohnfläche", "14.54 mqm Wohnfl", "Wfl 134 m qm"]
for x in strs:
	m = pat.search(x)
	if m:
		if m.group(1): # First alternative found a match
			print("{}".format(m.group(1), " - ", m.group(2)))
		else:          # Second alternative "won"
			print("{}".format(m.group(3), " - ", m.group(4)))