To be clear I generated seed words from newer version of Electrum. I don't know exact version but I run it from Tails OS that is maximum 1 year old, so it is definitely not Electrum older than 2015.
It doesn't really matter what version of electrum you are using. Electrum suggests words when importing a seed phrase since the version 3.1.3 which was released 7 years ago.
Therefore, Electrum 3.1.3 and all later versions suggest words from both BIP39 wordlist and electrum old wordlist when you import a seed phrase.