Can you change, let's say all Helvetica to Lato at a global level, similar to the Find Font functionality in other Adobe products?
Currently the only way you can global change the fonts is to select all the text objects and change them at once. You can add this feature request to user voice and track it there, I didn't see one specifically for Find Font: https://adobexd.uservoice.com. You can also add your voice to a similar feature which might work for you: Global Style Edits
Thanks for your feedback and thanks for using XD!
Here's a better solution, as of this writing: Under the File menu, select Package. Once in the Package dialog box, select 'Fonts'. Context naturally changes to show you a 'Find Font' button. Click that button. There you can make your global font changes to your document. The only caveat? Remember to simply Cancel the package operation to return to your document to inspect the changes.
There used to be a handy 'Preflight' menu option under the Edit menu for things like this, but I believe it's probably exactly the same thing we're looking at in 'Edit/Package' now. Meh. Go figure, right?