Hi Martin,
If I remember you are running PowerAMC 16.1 on MS SQL Server 2008 repository.
For your information with PowerAMC 16.5.3.3 (4371) - Latest version available and running on Oracle repository 12c.
I have the same result.
Repository - You can see Diagramme_1 - v1 - At the end
Local - You can see Diagramme_1 - At first
For your information
A) In "Option Générale" you have a field named "Tri" to sort objects name in numerical order. i.e. Table_1, Table_2 in the Workspace area but it's not your problem here.
B) This does not seem a problem about sorting objects with accents (as é è à ò, etc) . Previously it was but SAP has corrected.
I'll try later tonight with the English version to determine if I get the same result.
I think you must open a ticket to SAP