import re
 
teststring = '''#first-error-type: cjjyr901-d374-jfh73kf8k, 
#second-err, #some-other-error : jksdf89-123r-e3-1345r (some kind of note), 99f7yr901-374-jfh73kf8k 
#third-errortype cjjyr901-d374-jfh73kf8k, ksdf89-123r-e3-1345r, 99f7yr901-374-jfh73kf8k'
'''
new = re.sub(
	r'(#\w+(?:-\w+)*)(?=[:\s]+\w)[^\S\n]*(?::[^\S\n]*)?|,[^\S\n]*(?=\n)', 
    lambda x: f'{x.group(1)}: ' if x.group(1) else '',
    teststring)
print( list(map(lambda x: x.strip(), re.findall(r'#\w+(?:-\w+)*[,: ][^"\'\r\n]*', new))) )

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