Hey Ed,
I just tried this with a python document, and Bbedit is offering the correct suggestion, and once I hit tab to accept, or enter, it fills in the entire name
I defined a simple function with a_really_long_name and it worked.
Could it be your settings under Preferences/Completion:
According to the manual (pg 225) it states:
The Completion preferences control BBEdit’s text completion behaviors, including both the completion popup and automatic insertion of delimiters, which consist of parentheses, brackets, single and double quotes, as well as various language-specific elements.
If this doesn't work, send a help request. They're usually pretty quick to respond.
Thanks,
Rick