I am experiencing the issue that Fava shows many error messages "Invalid account name" in my beancount files. The issue is caused when two aspects come together:

1. we are using different top-level names (e.g. via option name_assets)
2. we include other files with transactions

As a small test case, consider this beancount file:

option "title" "Test case"
option "operating_currency" "EUR"
option "name_assets" "Aktiva"
option "name_expenses" "Aufwendungen"
2024年01月01日 open Aktiva:Bank EUR
2024年01月01日 open Aufwendungen:Food EUR
2024年03月11日 * "Supermarket"
 Aktiva:Bank -45.50 EUR
 Aufwendungen:Food 45.50 EUR

In this case, we use different top-level names for assets & expenses, but no errors are shown. However, if we add a line
include transaction.beancount and move/copy the transaction to the included file, we get two "Invalid account name" errors.

This behavior is shown when running Beancount version 3.2.0 and Fava 1.30.12.