At the last Advent penance service they began with all the priests at the altar and had a little talk on the benefits of confession, a communal prayer, then the priests fanned out to the various 'stations', mostly in the transepts, around the sanctuary, and the narthex, marked with a little barricade around for privacy. Most of course were face-to-face, sitting on two chairs, because there are only two confessionals. We had over a dozen priests in attendance.
Fun time last Lenten penance service, the retired archbishop came and brought a friend of his, a Cardinal, who happened to be visiting in town. That was pretty cool, he just took a chair and heard confessions like everyone else (I wasn't in his line - I went to my favorite confessor, who gives excellent advice and a penance that's stiff enough that you feel like he took you seriously). I wondered if you use a different formula with a Cardinal . . . "bless me your Eminence for I have sinned" . . . but I asked afterwards and you don't.
The way our confessionals are set up, you always have the option of going round to the other side for a face-to-face confession. They are only single-sided, not double sided like the old ones where the priest sat in the middle with a screen on each side. Now that I think about it, there should be plenty of room for a wheelchair to go around the back side of the confessional -
I kinda like the screen, but really don't have a problem with face-to-face. I lead a pretty boring life, and the older I get the less embarrassed I am about almost everything.
I would just lay your problem before the priest in your Email, and explain that you can't get the benefit of the Sacrament through the screen because of your hearing loss. I've found that most folks are perfectly willing to accommodate an honest problem or obstacle, if you just explain it to them in a straightforward way, as frankly as you can. And be as accommodating as you can to the priest if he suggests a solution.
The Canons (and the Vatican clarification of 1998) do give a priest the power to decide NOT to hear confessions outside the grille at all, and I don't imagine the FSSP folks are very keen on the idea of face-to-face, but the Canons also say that the priest should temper justice with mercy -- anyway, I'd ask.