Hi Geoffroy!

My first suggest is that you get latest Hamlib. Version 4.xx. You know it from rig models. With new one they have 4 digits. So your model will be 1024 then.
Be sure that your linux updates have not already installed new hamlib. In that case your rig will not work before you change model number from 124 to 1024.
Next test with different poll rates. Preferences/trxcontrol/radio one/poll rate. Try something between 1000 and 2500. Under 1000 may be too fast and cause errors that delay the reading, specially with 4800bps speed.

When you change band from TRControl buttons it changes rig's frequency quite fast but takes 2 poll rounds after rig has changed before TRXControl frequency display shows the new frequency.

I still guess that you can't complete qso within 10 seconds, so the right frequency will be there at the time of logging qso :-)

If you want deeper study you should run rigctld in command console with right port and speed setting parameters.
You see current ones if you start cqrlog and when it shows rig frequency open command console and give:
ps ax | grep rig
Then you see something like:
[saku@hamtpad ~]$ ps ax | grep rig
3828 ? Sl 0:01 /usr/bin/rigctld -m 3073 -r /dev/icom7300 -t 4532 -s 19200 -C auto_power_on=0
4417 pts/0 S+ 0:00 grep --color=auto rig

Starting from "/usr" up to line end is the string that you can use when you start rigctld manually from console.

In Preferences/trxcontrol/radio one set rig model to 2 (Net Hamlib rigctld). UNcheck "Run rigctld at program start". Close cqrlog.
Open command console and give the line you got with "ps ax"
In my case it would be:

/usr/bin/rigctld -m 3073 -r /dev/icom7300 -t 4532 -s 19200 -C auto_power_on=0 -vvvvv

Note to add "-vvvvv" as last parameter!

You get lot of text to console. When printing pauses start cqrlog and keep console still open and rigctld running.
Every time cqrlog polls rig you should see something in console. But not "error" lines.

There is quite lot of information. You can make it less giving just 3 "v" instead of five: "-vvv" at start line. Or 4 "v"s
You can stop rigctld in console any time with Ctrl+C