I don't know one Mac from another, but this might be what you are looking for: https://ftp.mozilla.org/pub/thunderbird/releases/115.16.2/mac/

Thank you. Looks like I need to keep looking.

128 likely isn't your problem. We need to sort out https://support.mozilla.org/en-US/questions/1465548

Each folder is the language locale abbreviation so for example the English options are en-CA, en-GB, en-US which Canadian, British, US.

Keep in mind that Thunderbird 115 was not really intended to be supported past Tb 115.15.0 with any more updates as to why there is no Tb 115.17.0

Thunderbird 115 support ending with 115.15.0 https://thunderbird.topicbox.com/groups/planning/T6689f5ad30cc4731

I have locked this issue. Let's first solve https://support.mozilla.org/en-US/questions/1440186