Where the Fourth English Word Looks

A translation transformer is being trained on one pair of sentences.

Training hands the decoder the whole English target at once. Each decoder block runs masked self-attention over the English tokens, then cross-attention into the encoder's outputs.

Now look at one position inside one decoder block: the row belonging to English token number $4$, counting from $1$.

Across that position's two attention sublayers combined, how many of its attention weights are non-zero?

Assume single-head attention in both sublayers, and take every unmasked weight to be non-zero — softmax never returns exactly zero for a finite score.