Pressing and releasing J works as expected:
43:Sep 15 09:45:42 Jolla harbour-tohkbd2[1513]: Processing report: 0b 00 ee 00 00 ca 00 00 00 00 00
44:Sep 15 09:45:43 Jolla harbour-tohkbd2[1513]: Processing report: 0b 00 ee 00 00 00 00 00 00 00 00

I will press and release right-shift:
45:Sep 15 09:46:05 Jolla harbour-tohkbd2[1513]: Processing report: 0b 00 ee 00 00 ea 00 00 00 00 00
46:Sep 15 09:46:05 Jolla harbour-tohkbd2[1513]: shift changed to down
47:Sep 15 09:46:05 Jolla harbour-tohkbd2[1513]: Processing report: 0b 00 ee 00 00 00 00 00 00 00 00
48:Sep 15 09:46:05 Jolla harbour-tohkbd2[1513]: shift changed to up

I will now press and release J again (this will input ctrl-J to any application):
95:Sep 15 09:46:55 Jolla harbour-tohkbd2[1513]: Processing report: 0b 00 ee 00 00 ca 00 00 00 00 00
96:Sep 15 09:46:56 Jolla harbour-tohkbd2[1513]: Processing report: 0b 00 ee 00 00 00 00 00 00 00 00

And again:
98:Sep 15 09:47:07 Jolla harbour-tohkbd2[1513]: Processing report: 0b 00 ee 00 00 ca 00 00 00 00 00
99:Sep 15 09:47:07 Jolla harbour-tohkbd2[1513]: Processing report: 0b 00 ee 00 00 00 00 00 00 00 00

Now I will press and release right-ctrl to reset the situation:
100:Sep 15 09:47:30 Jolla harbour-tohkbd2[1513]: Processing report: 0b 00 ee 00 00 bf 00 00 00 00 00
101:Sep 15 09:47:30 Jolla harbour-tohkbd2[1513]: ctrl changed to down
102:Sep 15 09:47:31 Jolla harbour-tohkbd2[1513]: Processing report: 0b 00 ee 00 00 00 00 00 00 00 00
103:Sep 15 09:47:31 Jolla harbour-tohkbd2[1513]: ctrl changed to up

Now J works as expected again:
104:Sep 15 09:47:43 Jolla harbour-tohkbd2[1513]: Processing report: 0b 00 ee 00 00 ca 00 00 00 00 00
105:Sep 15 09:47:43 Jolla harbour-tohkbd2[1513]: 100 interrputs in 501816 ms
106:Sep 15 09:47:43 Jolla harbour-tohkbd2[1513]: Processing report: 0b 00 ee 00 00 00 00 00 00 00 00

And again:
107:Sep 15 09:47:48 Jolla harbour-tohkbd2[1513]: Processing report: 0b 00 ee 00 00 ca 00 00 00 00 00
108:Sep 15 09:47:49 Jolla harbour-tohkbd2[1513]: Processing report: 0b 00 ee 00 00 00 00 00 00 00 00