The mod can be translated to other languages.
The mod link: https://disk.yandex.ru/d/m9x9xHQhbEGsmA (do not use the Workshop version, it is outdated)
If you want to do all work effectively, use Total Commander or any analogues.

What needs to be translated:
1. ini files - Data\INI\Items
- The main file, ITEMINFO, contains all descriptions for the mod's items
You should take the english ITEMINFO (7.62 Hard Life/Data/HardLife_En.zip/INI/ITEMS/ITEMINFO) and carefully "join" both files. Be attentive, some description were changed. The most time-consuming part, if you're planning to do the work well. Otherwise, you can just copy all descriptions 1:1 from the original files by the item name, but in any case new entries need to be translated manually, as there are no translation files for the ARM/7.62custom mod.
- AMMOINFO (contains some description strings in russian)
- KEYITEMS - the same as for ITEMINFO, but the amount of text is minimal

2. Hardlife files:
- WEAPONORDERPLAYERBASE.INI
- WEAPONORDERCALICANTINOS.INI
- WEAPONCLEANING.INI
- cars.xml
Those are a bit more more complicated.
Most (!) of entries are the same as for original mod, so in 95% you do the same.
Say, you're translating cars.xml - in this case you need to find cars.xml in 7.62 Hard Life/Data/HardLife.zip/HARDLIFE/, and compare both files with Total Commander (files comparison).
If you see a translation string, like name="lang/cars/upg/armor" - do nothing, it should work well for you.
If you see a name like name="Броня", you need to replace it with the proper localized string (template, or just a raw string). In TC comparison mode look at the original file, and find the same item, in this case you will see something like name="lang/cars/upg/armor" (or just compare files by opening it simulatneously in adjacent editor windows, but it is harder).
When you got the localization string, go into lang.en.zip in Total Commander, press Alt+F7, check "with text" flag, enter lang/cars/upg/armor in the field --> Enter.
You will find the cars.lang.en.xml (you can just search in all xmls manually) - open it, find the template and compare its value "Armor" in this case with the string translated by you. If it is the same, then replace the russian name with the english raw text, or with the localization template ("lang/cars/upg/armor").
If it is NOT the same (in case if I changed some descriptions), then you better to use the correct translation.

3. Upgrade names:
762custom for HLA 1.0\Data\Hardlife\items\weapon_upgrades.xml

4. LUA scripts - 7.62 Hard Life\Mods\762custom for HLA 1.0\Data\Hardlife\lua\
As most of scripts were changed, so you need to revise all, but the amount of translated data is low.
Again, if you see the localization template like _t"lang/cars/repair/heavy_damage" - do nothing.
If you see russian words there - good luck :)
Say, you have a weird string
monster:Say("Необходим мультитул или ящик с инструментами.")
Most likely you won't find the exact string in localization files, so you need to use online translators - just be aware, that AI-based translators like DeepL, may "hallucinate". Check use-cases for this phrase to be sure.
In this case the result should look like
monster:Say("Multitool or toolbox needed")

As most of the localized strings are for displaying, the most popular thing to display is the Say command, so search for ":Say(" entry.
If you're familiar with regular expression, look for ":Say(" parts which doesn't contain "_t"lang" part after it.
Other translated option are the context menus: search for "AddItemContextMenu".

5. GUI - 762custom for HLA 1.0\Data\BMP\HUD\
I used some textures from this mod: https://steamcommunity.com/sharedfiles/filedetails/?id=2276997459
So all that you need to do is to replace appropriate image file.

6. The last step (optional) - translate loading hints (TIPS.TXT)

P.S. In addition to the mod files, you will need to translate the FAQ too, as it contains many important notes (at least the weapon modifications variants).