Hi Martin, a little bit more information to read through;
To my knowledge erasing, destroying of (foreign) invalid hallmarks in the Netherlands and Belgium was not a common practise. I have noticed it on Imperial Russian silver where the old hallmarks of the Tsar era were destroyed/erased and replaced by Soviets hallmarks. I do not know what happened to your silver perfume flask and what has been erased. Perhaps the essayer made a serious mistake and had to correct/erase the error(s). What is the size of the flask, could it have been part of an assemble?
Belgium 1832-1869
The assay offices
The assay offices were kept open after the Belgian uprising against the Dutch regime, except for the cities of Maastricht and Luxemburg who remained occupied by Dutch troops. The administrative centre of the province of Luxembourg was transferred to Arlon by resolution of 16 October 1830, and an assay office was established in Hasselt in order to replace the one in Maastricht.
The marks
A resolution of August 18th 1831 stipulated the use of the new marks in Belgium. The seals were only at the disposal of the assay offices around 1 march 1832. Meanwhile, they kept using the marks from the Dutch era.
The assay mark
Resolution of 14 September 1814, continued to be in force, so the alloys of the Dutch era remained unchanged.
The assay office hallmark
The assay office hallmark pictured Minerva’s head wearing a helmet with a letter which identified the office. The letters remained the same as in the Dutch era.
The marks foreign and recence
A mark
foreign, showing the gothic letter E was assigned to those works imported from abroad. It did not guarantee whatever alloy
A mark
recense, showing the gothic letter R, was for free, but could only be put on objects already carrying the assay marks or assay office
hallmarks of the Dutch era, within two months time as of 1 March 1832. The works of the French era or of the Ancien Regime were classed with foreign works and had to be marked within the same period of time with the mark for foreign work E serving as recense.
Not to make it easy. The Dutch and Belgian sword marks according literature;
Above from Walter van Dievoet Algemeen repertorium van de edelsmeden en van de merken van edelsmeedwerk in België
Below from Het Zilver Lexicon
Peter.
Source; Walter van Dievoet Algemeen repertorium van de edelsmeden en van de merken van edelsmeedwerk in België II 1798/1942
Janjaap Luijt Het Zilver Lexicon