First, as for how to get the string as you want it, it could be helpful if you changed the writedump to not do format "text" (leaving it as the default of html), so that you'd see more readily in the dump what the kind object it is was.

As for what you DO show, it seems that the returned object (in that variable you are dumping) is itself a complex object with methods you then need to call. 

As for the difference between the current dump in CF and that in Lucee, and the fact that you see some of the "string" you want to "extract", I think it's that Lucee is going ahead and calling those methods (assuming it can, with no arguments), and if it has a result it's showing you. That's a convenience, but not any indication that CF is doing something wrong. Indeed, the screenshot of Lucee does not show WHAT the method names are, but the CF one does. (So each has its value, that the other does not.)

And so it looks (from the dumps of each engine) that the method you want is perhaps the geterrormessage, so do this:

writedump(xlatstring.geterrormessage());

Again, no need of the format argument. Does it have what you want? If so, then you don't need the writedump any more. You could assign that method call to a variable and do what you will with it (show it on the page, send it in an email, store it in a database). Same for the other methods. Just do a dump of each method.

And I will remind you as I did early on that if you were to visit this web service using a generic web service browsing tool like soapclient.com, you would have had all these answers without writing a line of CFML.

Finally, as for us trying to help you with such issues, it would have been very helpful if you would have also provided a link to the trycf snippet that you created and show below. I could have readily tested things out and confirmed that that method or other methods provided useful string results. As it is, I have to guess. And the values in the args you pass TO the consultarfc are just a bit too complex to easily type.

Let us know if this gets you going.