Is transignification similar to a Lutheran understanding?
From what I understand of our doctrines: not necessarily. Like you said for the Catholics, we emphasize the substantial and bodily presence of Christ in the sacrament, that we really do eat and drink his body and blood (one thing that Philip Melanchthon got in trouble later in his life, he started calling the Gnesio-Lutheran viewpoint "bread worship", and he adopted something more like receptionism, something a classical Lutheran viewpoint would deny). If a person is using transignification as a way to deny this reality, then it's probably something a Lutheran could not accept.
Luther himself seemed to think transubstantiation was an acceptable explanation, but he did not believe based on the text of the Scriptures that it should be required to be believed. Some of our later confessions seem to reject it, though.
I do know the Lutheran World Federation has had a lot of agreement with the Catholics, and especially the Orthodox, on the doctrine of the sacrament. But awareness of this doesn't seem to always filter down to individual pastors.
Now me myself, personally, I do think potentially transignification is an acceptable way to approach the sacrament, provided that we understand symbols as mediating reality. But not everybody understands symbols this way, due to the influence of various philosophical assumptions. I guess I would be tempted to say the bread and wine is transfigured by Christ's presence. I actually think this fits with the classical Lutheran theology of the
genus maiesticum the best.
The Eucharist