import re
text = r'ced"|"ms|n"|4|98'
pattern = r'"?\|(?!(?:(?<=[A-Za-z]\|)|(?<=[A-Za-z]\\\|))(?=[a-zA-Z]))"?'
print( re.split(pattern, text) )
# => ['ced', 'ms|n', '4', '98']
text = r'ced"|"ms\|n"|4|98'
print( re.split(pattern, text) )
# => ['ced', 'ms\\|n', '4', '98']
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