The writing system (P.O.J.) loosely describes the way Hokkien was spoken in Xiamen (廈門) around 1870. It applies to 21st century Taiwanese Hokkien very loosely (there are ongoing debates about how many distinct consonants people should use when writing Hô-ló, even amongst those who want to abolish Romanization entirely). You'll notice several points in the chart in which I question whether or not the textbook I'm using has made an error --but it is an open-ended question. I will now rely on suggestions form native speaker to let me know if I've figured out the puzzle.
It's very hard for me to say with certainty that ló is an error for lŏh --I can only suggest what seems to make sense to me, and then wait for feedback from native speakers. Given how approximate the spelling system is, it is entirely possible that both spellings are acceptable (or that ló is now a better transcription of what the old dictionaries list as lŏh). It is entirely possible that the new generation of dictionaries using Zhuyin (注音, a.k.a. bopomofo) will end up influencing the way that people use the "old" methods of spelling Hokkien in Roman letters. It is also possible that reverse-transcription from the Taiwanese government's official list of Sinograph-based spellings (available here as a PDF) will end up influencing Romanization through "reverse-transcription".
Displaying information schematically gives the impression that you're presenting more when (in fact) you're presenting less. The chart that here seems to present the answers to many questions; in fact, it raises more questions than it answers.
