Account value update and its impact to reconciliation or future/existing transactions

Currently, we have a mapping set created in procurement where account (part of COA string) value gets picked up based on item category and expenditure type used in the requisition creation. We have already created a few transactions with the existing setup.

Now, the users want to update this account value to a new value and wanted to understand any challenges due to this change either for the existing/future transactions or during month/year end reconciliation. Any workaround to avoid the impact? Please help to understand this scenario better.