And this gives us a very useful research target

The baptism record does not name Pierre's parents.

It only says:

Petrus Lagasse + Joanna Bertran → Ludovicus

So the record proves the Pierre → Ludovicus relationship, but it does not yet prove:

Michel Lagasse + Laurance DeVimeur → Pierre Lagasse

That remains the critical link.

However, your Filae record gives Pierre as:

Pierre LAGASSE

born about 1674, Le Nouvion-en-Thiérache, Aisne

parents Michel LAGASSE + Laurance DEVIMEUR

wife Jeanne BERTRAND

children Maria, Marie Françoise, Jeanne, Ludovicus, Anne Maria

The next step is therefore very focused:

Find Pierre's baptism at Le Nouvion-en-Thiérache around 1674.

If the original register gives:

Petrus/Pierre, son of Michael/Michel Lagasse and Laurance DeVimeur

then we have the documentary bridge you've been looking for.

And because you have two DNA matches with Bertrand ancestry, I would also pursue the godparent column very carefully. A Bertrand sponsor connected to Ludovicus could potentially give us an additional clue about Jeanne Bertrand's family.