Subtitle Edit - Check split lines when character limitation not met

I am a professional subtitler, and usually work with Subtitle Edit, and I have a question about a particular check that I would like to make on my translated .srt files.

Industry specs ask that the character limitation is 42 characters per line. If the entire subtitle is below that limitation (and it is not a dialogue), it should be condensed into one line. Sometimes, when translating, you can forget and have a subtitle like this:

I wanted to let you know
that I am back.

This is 39 characters long, and would become 40 when condensed in one line. Therefore, the above subtitle would be considered wrong and need to be amended. I wonder if there is a subtitle editor that I can use to check for all events that meet the following criteria:

1. The total character count is 41 or less.
2. The number of lines is 2.

Do you have any idea about how to manage something like this? I have also thought about opening the .srt in Excel and try formulas, but Excel does not seem to handle these files very well.

Thanks!