Previous string value in trigger description

[markz]

Hello,

need help to show previous string value in trigger name (description). Zabbix v3.4.9

Trigger name:

Firmware has changed on {HOST.NAME} from {{ITEM.VALUE2}.regsub("\d+(\.\d+)*",\0)} to {{ITEM.VALUE1}.regsub("\d+(\.\d+)*",\0)}

Trigger Expression:

({Template SNMP Mikrotik:routeros.version.change()}>0) and ({Template SNMP Mikrotik:routeros.version.strlen(#2)}>0)

but this doesn't work, it shows the same value. Example:

Information 21.05.2018 00:00:26 21.05.2018 01:00:26 RESOLVED RB850Gx2-1 Firmware has changed on RB850Gx2-1 from 6.42.2 to 6.42.2

2018-05-21 02:00:26    6.42.2
2018-05-21 01:00:26    6.42.2
2018-05-21 00:00:26    6.42.2
2018-05-20 23:00:26    6.42.1
2018-05-20 22:00:26    6.42.1

[Engraf]

The macro {ITEM.VALUE<1-9>} provides an ITEM value that used in trigger expression but not expression value itself ( i.e. host:key but not {host:key.func(param)} ).
I do not see how you can get previous value in trigger name. It has a limited set of supported macros (see manual).