Statements line amount with a different journal currency

I found out a behaviour on statement which is not consistent:
On simple case with company with same currency as their bank:
When you have a origin statement line of +100€ and you create a line and select your invoice of +50€, the amount updates to 50€.
Since here, all ok, let’s jump to a bit more complex example:

Company with currency on euro.
Bank in dolars and the journal defined on dolars. Also currency rates are activated.
On a statement with orgin line on date 14/12 (1€=1.1309$) with amount +140$ and you select your invoice of 50€ the amount on the line remains the same (+140$).

The ideal should be to update the amount once the invoice selected to 56.56$.

For now the code (that split lines) explicitly ignore journal in different currency than the company.

I do not see how you want to do that. For me it will almost always never match the invoice amount due to currency rate changes.
The reconciliation of statement in different currency is probably better managed by launching the reconciliation wizard where we can book exchange rate difference.