I'd be more worried about decimal data types being interpreted as floats. That could get gnarly fast on the wrong language runtime, and is partially why Cobol programmers are still in demand in the financial sector.
the beauty of bref is you work with the same php engine as before. I am a (very) long time PHP developer, my primary work is still Drupal so the ability to make a small serverless app in PHP was very handy for me. My app implements a webhook and I feel Lambda is made for this: the script is small and quite fast, it checks the payload and puts an item into SQS as appropriate. Then another infra can slowly empty the SQS queue. The problem here is the load is insanely spikey -- sometimes tens of thousands of requests in a very short time frame, sometimes nothing. Directly writing this into a transactional database would require very costly infra. The Lambda-SQS model smooths it out. It's fine if some changes take minutes or even hours to be recorded.