If you know what the sheet attributes will be ahead of time, you as the GM, can create macros that work off of those attributes and provide them to your players. Assuming, of course, that you can even refer to a Journal's attributes that you don't have control of... I've never considered where that would actually be a thing :) It Shouuuuuld work though. You can create macros using their Attributes instead of raw values. ( [[1d20 + @{JournalName|AttributeName}]] instead of just [[1d20+5]] ), but as soon as they roll anything they can mouse over the result to see what their bonus' are. Additionally, they could just use "/talktomyself" and hit all the buttons to see them ahead of time. The only way, outside of the API (which if you say three times in a forum post will cause the demon, The Aaron, to appear), for you to give your players macros where the bonus' are hidden from them, would be to give them raw dice Macros and you, as the GM who has access to their sheets, mentally add their bonus' to it on the fly. Either that our you roll FOR them, which is rarely a good idea.
