Can you show me where SFX says the wrong number - screenshot.
Re editability, with your method you end up with a flattened TIF file and, as you say, you have to start all over again if you change your mind. Now with the LR > PS SO method, my TIF might have a single layer but it is a smart object layer with the SFX adjustments shown as a smart filter (see attachment). So tomorrow I see the TIF in LR and decide I want to change a control point. I open in PS, choose Edit Original, and PS opens. I double click the smart filter, SFX opens, and all my control points and other SFX settings can be changed. I find this so useful that it's my default way of working with SFX.
There are other advantages of using smart objects. For instance, in PS you can drag the SFX edits (the smart filter) from one image to another, great if you're doing a set of images with a common look.
Another example is if I am already in PS to do "other things" such as cloning, but then want to apply SFX and keep the adjustments editable. I'll select all the layers, convert them into a single smart object, then launch SFX. The result is like the attachment and I can double click the SO to go into the layers, or double click the smart filter to change the SFX settings.