This thread is resolved. Here is a description of the problem and solution.
Problem: I typed in the keywords to search the target string. Then find the target strings and click the right hand side button to type in the translated wordings. Solution: The theme uses a proprietary builder for the homepage. All the options can be found under admin_texts_dp_options on String Translation. If you cannot find them there yet, just go to String Translation → Translate texts in admin screens and you can find the text under dp_options. Just check the fields you want to translate and that's all.
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