import re

validation = """
Message: Less than 1 values on Work->bf:language
Message: Less than 1 values on Work->bf:content
Message: Less than 1 values on Work->bf:adminMetadata
"""

missing = re.findall(r"Less than \d+ values on.*->bf:(\w+)", validation)
print(f"Found properties: {missing}")
print(f"Unique: {set(missing)}")