Hm... interesting. The problem is that in your descriptive text, Final Draft doesn't see any difference between the word, "Frank" and the word, "banana" unless you tell it they're different. Therein lies the problem.
I tried creating a custom element but could not get the programme to recognise the custom element as a character.
Not sure my solution is that practical but this is about the best I can come up with. NB: I'm using Final Draft 6 (not so keen on 7) users of 7 may know of a better way to do this since the upgrade. I'll look into it.
OK. Using your example, this is the troublesome scene...
EXT. HOUSE - DAY
Tom and Frank leave the house and walk down the street.
What you need to do is rewrite it so it looks like this...
EXT. HOUSE - DAY
Tom
and
Frank
leave the house and walk down the street.
It's important you put each character on his own line otherwise any surrounding text will be incorporating into the character name.
Then, highlight "Tom" and go into your elements drop-down box. Select "Character". It will move Tom into the dialogue section of the page and capitalise his name. Do the same for Frank. It doesn't matter that there's no dialogue beneath them. It'll look something like this...
EXT. HOUSE - DAY
TOM
and
FRANK
leave the house and walk down the street.
Generate your statistics report and they'll appear in the scene. You'll then have to go back and reformat those words so it doesn't make your script look weird.
Not the best solution but I can't think of what else to suggest. At least this way (with a bit of extra work depending on how many scenes you have) you can achieve what you want. Will keep digging.