Not sure where that idea called Hebrews letters comes from? Scripture informs us that without parables Christ spoke not and has given us the tools to rightly divide that manner of prophecy . But this manner you call Hebrew letters .I don't see that as prophecy.
There is very little information in the Bible about Bats. Almost nothing. But if we study the letters then we can start to learn something about them and why we are prohibited from eating them. Moses just said do not eat the bat. If we want to know why then we have to put some effort into a study of the letters that make up the word.