I added lines 340 and 341 following the else. That solves my problem.
else:
# Skip lines without a tag -- Added by David Bailey
return False
raise PBNDecodeError("Expected a tag", curline, self.lineno)

BBO will not open/read these .lin files. I know the .lin files that I create are much, much larger that BBO would expect. So I created one with only 24 deals. BBO will not open/read it either. Here are the first four lines...

pn|-,-,-,-|st||md|3S35AH45AD238TQACJ,S9TQH689D456KC34K,S47JKHTQKD7JC278Q,|rh||ah|Board 1|sv|o|pg||
pn|-,-,-,-|st||md|4S689H47D2356C5JQK,S7TJKAH35689ADKCT,S245QHJKD489C4689,|rh||ah|Board 2|sv|n|pg||
pn|-,-,-,-|st||md|1S9H3789D38KAC79JA,S45JH4JAD567TC56T,S267TAH6TQKDQC38K,|rh||ah|Board 3|sv|e|pg||
pn|-,-,-,-|st||md|2S3TJH45JQD26C249A,S45KAHAD378TC68TK,S6789H79TD45JC7JQ,|rh||ah|Board 4|sv|b|pg||

UPDATE: If I delete the pn|-,-,-,-|st|| at the beginning of each line, BBO will import the file.

I wrote a simple program to comment any 'statistics' in pbn files. These lines are still in the pbn files with an '# ' as the first two characters of the lines.

I printed them to stats.txt. Have a look.

https://github.com/ADavidBailey/Practice-Bidding-Scenarios/blob/main/stats.txt

pn|-,-,-,-|st||md|1S9H3789D38KAC79JA,S45JH4JAD567TC56T,S267TAH6TQKDQC38K,|rh||ah|Board 3|sv|e|pg|| pn|-,-,-,-|st||md|2S3TJH45JQD26C249A,S45KAHAD378TC68TK,S6789H79TD45JC7JQ,|rh||ah|Board 4|sv|b|pg||

UPDATE: If I delete the pn|-,-,-,-|st|| at the beginning of each line, BBO will import the file.

BBO relies on the qx|o1| to display the imported board number correctly. I wrote a program to insert the board number after the '0'. Now, they're like this for boards 9 and 10:

qx|o9|md|3S2TKH37TQD4KAC45J,S589AH45JKD25TQCQ,S67JQH9AD379C678T,|rh||ah|Board 9|sv|e|pg||
qx|o10|md|4S369QH239TD5JAC2Q,S47TJKH456JD9C9KA,SAH78QKD236QC578J,|rh||ah|Board 10|sv|b|pg||

They seem to work everywhere.

thanks for persevering with this, i will try and collect all the lin fixes and update the parser!

Per advise of Thorvald, I changed the comment line 1st character from # to %