[2] Maillard missed the start of the 2018–19 season with a lower body injury before being assigned on a rehab stint with HC Sierre of the MySports League.

After having played 12 games with Sierre, putting up 10 points (3 goals), Maillard returned to Geneva and made his NL season debut on November 20 at home, against HC Fribourg-Gottéron.

[3] Maillard struggled to produce offensively during the 2019–20 season and was sent on a loan to HC Sierre of the Swiss League but only appeared in one game, scoring one goal, before being called up by Geneva.

On 23 August 2020 Maillard was traded, along with Floran Douay, to Lausanne HC in exchange for Tyler Moy.

On 1 December 2020 Maillard tore his ACL during the Swiss Cup 1/4 finals in his first game against his former team, Genève-Servette HC.

Maillard returned to game action with Lausanne on 10 September 2021 in a 3–2 loss to EHC Biel to kick off the season.

[8] Maillard was named to Switzerland's under-20 team for the 2018 IIHF World Junior Championships in Buffalo, New York.