First, for these accounts, the end date must be removed.
Then, the translations must be updated to make sense for 2019 and 2020 accounting.
For example :
From 01/01/2020, Account 141 become 1411.
Account 1411 become 1412.
When 2019 accounting will be finished, a procedure must be launched to update main account number. The selected translation will be used as number and name.
To launch it, a button exists on Chart of account screen : “Change Number and Name”. Choose your preferred language and chart of account type :