I assumed that all existing do-not-break-after lists are currently used with actions that use do-not-break-after lists. However, this does not appear to be the case. I did some experiments with clicking on "Auto br" with some selected sample subtitles. With this, I only saw items from the English do-not-break-after list to work as expected. I tested with items from the German / Polish / Portuguese / Romanian lists that have the same length as the items used from the English list — but these German / Polish / Portuguese / Romanian items did not work as expected. So it seems that currently only the English do-not-break-after list is used by Subtitle Edit.
This image shows the line breaks created in the selected sample subtitles by clicking the "Auto br" button with a checkmark at "Use do-not-break-after list":
Notes on these sample subtitles:
"Dr" and "Mr" are in the English list.
"so" is in the German list and not in the English list.
"Pn" is in the Polish list and not in the English list.
"Sr" is in the Portuguese list and not in the English list.
"Dl" is in the Romanian list and not in the English list.
[Subtitle Edit 4.0.8. Settings/General/Rules: Single line max. length = 46; Max. number of lines = 2; Unbreak subtitles shorter than = 33. Settings/Tools/Auto br: Only a checkmark at "Use do-not-break-after list".]
This image shows the line breaks created in the selected sample subtitles by clicking the "Auto br" button without a checkmark at "Use do-not-break-after list":
I assumed that all existing do-not-break-after lists are currently used with actions that use do-not-break-after lists. However, this does not appear to be the case. I did some experiments with clicking on "Auto br" with some selected sample subtitles. With this, I only saw items from the English do-not-break-after list to work as expected. I tested with items from the German / Polish / Portuguese / Romanian lists that have the same length as the items used from the English list — but these German / Polish / Portuguese / Romanian items did not work as expected. So it seems that currently only the English do-not-break-after list is used by Subtitle Edit.
This image shows the line breaks created in the selected sample subtitles by clicking the "Auto br" button with a checkmark at "Use do-not-break-after list":
Notes on these sample subtitles: "Dr" and "Mr" are in the English list. "so" is in the German list and not in the English list. "Pn" is in the Polish list and not in the English list. "Sr" is in the Portuguese list and not in the English list. "Dl" is in the Romanian list and not in the English list. [Subtitle Edit 4.0.8. Settings/General/Rules: Single line max. length = 46; Max. number of lines = 2; Unbreak subtitles shorter than = 33. Settings/Tools/Auto br: Only a checkmark at "Use do-not-break-after list".]
This image shows the line breaks created in the selected sample subtitles by clicking the "Auto br" button without a checkmark at "Use do-not-break-after list":