Currently, more than 15 triggers are not displayed. The upper limit is hard-coded.
I believe that we should create an option to set this limit. (like defines.inc.php or USER PROFILE:Messaging)

If you change a fixed PHP/JS source, notice that more than triggers are displayed.

/usr/share/zabbix/js/class.cmessages.js

< pipeLength: 100, // how many messages to show
—
> pipeLength: 15, // how many messages to show

/usr/share/zabbix/jsrpc.php

< 'triggerLimit' => 100
—
> 'triggerLimit' => 15

< if (count($usedTriggers) < 100) {
—
> if (count($usedTriggers) < 15) {

There was no problem with 100 displays.