I have the same problem with lxinput_0.3.5-1_i386

I wanted to set the repeat rate slower because I find difficult to enter the passwords

I'm going to 'Preferences'-'Mouse and Keyboard' and set to the keyboard delay 1000 and interval 125

and then 2 files are updated:

1) in /home/myuser/.config/lxsession/LXDE/desktop.conf 2 lines are changed:

Delay=1000
Interval=125

All OK.

2) but in /home/myuser/.config/autostart/LXinput-setup.desktop this line looks like this:

Exec=sh -c 'xset m 20/10 10 r rate 1000 125 b on'

and this is an ugly bug

The 'xset r rate' syntax is

xset r rate 'delay in miliseconds' 'repeated keys per second'

but the repeated keys per second are in inverse relation with the interval.

repeated keys per second = 1000/interval

In my case it would be 1000/125 = 8

and the command should be

xset r rate 1000 8

The workaround is editing manually this file. But I expect this bug to be fixed.