The problem is with how the title and series information in these books are presented. These two books are a different and the parsing title didn't take this into account.
The two problems are:
- "6th Target (Women's Murder Club #6), The" - This is the title returned by the API. Having ", The" at the end is unexpected. It probably means that the title has been entered somewhere as "The 6th Target (Women's Murder Club #6)" rather than "The 6th Target" with separate series information.
- "Deuteronomy 21:10–34:12 (Word Biblical Commentary, #6B)" - In this case, the title and series is presented as expected. But, the series index is "6B". Calibre only allows numbers for the series index. The conversion from "6B" to a number fails and triggers the error.
The attached beta has fixes for these problems. Parsing the title to get to series info has been changed to handle the first example. For the second, the error is handled by not setting the series index. There is no way to know what should be done in situations like this. It could be 6.2, or maybe this is hexadeximal an should be 107, or maybe just 6. And I'm sure there are other strange numbers used.
Please try the beta and tell me how it goes.