HI,
According to a friend, there is nothing remotely named Finadene in Filipino traditions.
However, there is a tradition of making dipping sauces called sawsawan, which varies from person to person. It be made at the table from a range of available ingredients: fresh kalamansi (rarely the Mediterranean lemon unless it's the only thing available), vinegar, soy sauce, bagoong (fermented fish), fish sauce, hot sauce, herbs or chopped onion, garlic.
Suspect that finadene is probably not always made with the Mediterranean lemon either.
Googling "citrus in Guam," they use a range of different citruses including calamansi, which is highly represented in Filipino cuisine.
Have fun in your search!
Regards,
Cathy2