I need to find 4 different text strings in a text field called comments. Then I need the four text strings to populate 4 different fields in the same record. I don

If you want to action to happen when you exit the field, you will need to use a plugin. The calculations themselves will be in a script that will have 4 set field script steps (one for each of the target fields).

Without a plugin you'll need to put a button on the layout for the user to click. That button will run the same script as the event trigger plugin would.

It all depends on the purpose of the 4 fields. They can be either calculation fields, or text fields with auto-enter calculation (replace existing value).

In both cases the fields will update as soon as the user tabs out of the field referenced by the calculation. No plugin is required.