I started translating from the beginning, which was missing, which adds up to about 4% for today.

SL.29

Translated: 54%
WinSCP 6.5.2

Source commit: 4fa30b8eeea3b38a21b15b885e9894a8454db8b1

translations/version.ini

@@ -33,7 +33,7 @@ SK=72
 CH=142
 SQ=3
 TR=68
-SL=28
+SL=29
 LV=16
 UK=45
 BG=17
@@ -92,7 +92,7 @@ SK=2005,2025,Marián Hikaník,Patrik Lenart
 CH=2005,2025,Mark Lin,Walter Cheuk,Hong-Yi Chen
 SQ=2005,2019,
 TR=2004,2025,Kaya Zeren,Fatih Savas,Kerem Emik,Süleyman Şentürk
-SL=2006,2019,Aleksander Hegler,Renato Lukac
+SL=2006,2025,Žiga Vodnjov Frelih,Aleksander Hegler,Renato Lukac
 LV=2004,2019,Henrijs Kons,Vairis Caune
 UK=2006,2025,Oleksii Petrov,Ivanka Skakun,Martyniv Alex,Oleg Butuzov
 BG=2004,2021,ССТАНЕВ,Plamen Penev