Elmiko,
I understand your point, and it is extremely reasonable.
On one hand you are completely right, as I admit that sometimes Spanish sorting might sound bizarre to an English speaker. But also have in mind that, to a Spanish speaker "lo" is only the singular form of "los", and it would be really difficult to understand that a given sorting rule applies to "los" and not to "lo". Also, from a Spanish speaker's point of view if a sorting rule applies to articles it should apply to
all articles, and that's it... even if it sounds weird in English (and probably in Spanish).
To all "standard" articles, at least, as I said in my previous post. We can (and perhaps should) leave out freom this discussion the contractions "al" and "del", that technically are articles - although not included in the "really 100% standard articles" list that we all memorize at school and never forget
By the way, in the two examples you mention "lo" does not behave as an article but as a direct object (somehow replacing the English "it", not the English "the") and are two cases were Calibre manual title sort will have to come into action

, but it does (behave as an article) in many others, that do not sound so strange when translated: "Lo peor de cada casa" --> "peor de cada casa, Lo", "Lo más triste de mi vida" --> "más triste de mi vida, Lo".
Best from Madrid (well, from Málaga right now, accidentally),
-Enrique