Need a date parser for my custom date fielsd

Elastic Stack Logstash
2

You probably need to strip away the "th" (and "nd" and "st") that can come after the day as the date filter isn't capable of ignoring it automatically. Or, specify multiple date patterns and let the filter try them all until it gets a match. Untested:

date {
  match => [
    "name-of-your-field",
    "MMM dd'th' yyyy, HH:mm:ss.SSS",
    "MMM dd'nd' yyyy, HH:mm:ss.SSS",
    "MMM dd'st' yyyy, HH:mm:ss.SSS"
  ]
  locale => "en"
}