Well, we need to know that m is 6, and e is 3, and so on. Here, I've used the feature that permits tr operands to be delimited with arbitrary balancing punctuation, together with the optional whitespace that can be between the old list and the new list when we use such delimiters. This gives a nice visual layout to let me verify that I've got the right characters with the right translation. Now we need to walk the dictionary. If we use a hash keyed by the translated number, each element of the hash can have a value of an arrayref of all the words that matched.
Every value is an arrayref, consisting of the words that had that particular translated number.
If there's more than one entry, we have had a collision. The longer that collision list is, the more we're interested in it. That's more interesting to us than merlyn which seems to map into its own universe there. So now it's time to walk the resulting data structure and find the longest of those collision lists. This uses the arrayref from the value of the hash, dereferences it as an array name in a scalar context, which results in the number of items in that array.