Finally got sick of them and totally rebuilt.
First, separate data from presentation: all the data goes into a simple sheet of columns: date, amount, category, subcategory, memo. Auto-calculate columns for month, quarter, and final amount including sign depending on income or expense (as determined by category.)
Another sheet for two columns of categories and subcategories.
Infinite additional sheets for pivots based off of the original data.
Write a simple Excel macro in VBA to take all the existing data and slurp it into the correct format.
Drop the whole thing into Google drive for cloud access (bonus: as a native Google Sheet, it doesn't count towards Drive storage quota.)
Adding new expense items from mobile is still kind of annoying, so:
Use Tasker and 3rd party plugin to create a simple action that reads the category and subcategory columns, populates selection lists, shows a simple input screen for amount, category, subcategory, and memo. On save, writes the data down to a new row in the spreadsheet.