There have been riots in the Netherlands and demos in Austria. Clearly, we have a Covid economy. Therefore, would it be wise if the royal ladies dressed in a discreet way for a while? For instance, for the first Oslo banquet, Queen Maxima was just covered in ice and for the German state visit, Queen Margrethe glittered in the evenings. I think this is a time to cut the ice for a while, until the economies pick up some.
I have a similar feeling, but maybe the mood in the Americas (North and South), where Covid hit much harder, is different from that in Europe.
I don't think there is much public outcry against royal gala events in countries like Denmark and Sweden. There is some, however, in Spain. I read comments on YouTube for example complaining about Queen Letizia's appearance with the Russian tiara at President Mattarella's state dinner while "Spaniards are queuing in social restaurant lines and cannot pay their heating bills". I also saw complaints saying that there are still capacity restrictions on indoor dining (or at least recommendations) in Spain, but that was apparently ignored by the Royal Household (I don't know if that is accurate).
Interestingly the royalists/monarchists who were taking part in the discussion replied that, in any case, the King is not to blame, but rather the government (currently, in Spain, a coalition between socialists and republican communists actually), since it is the government that decides whether a state visit should go ahead or not, and the King only does what he is told. I guess that is a fair point.
In any case,as much as I like to see the gala dinners back, it may be too soon, especially with the current fourth wave in Europe.
We have seen it with Queen Maxima, how she slowly re-introduced the Stuart parure. An earring here, a necklace there... and after a while the small setting of the tiara came out. It was a good strategy, and imho it would also be a good strategy to follow with the jewels of the late Queen Fabiola. Just wearing one strawberry leaf as a brooch could be easily done. And like you, the fact that we haven't seen a single piece from Fabiola aquamarine collection makes me pessimistic.
The Belgian royals seem to own jewelry that, for different reasons, they do not wear or simply disappears. For example, the diamond necklace (with matching earrings and bracelet) that Queen Paola got as a gift from the Congolese dictator (was it Kabila?). As far as I understand, they are now part of the Royal Collection and never saw the light of day. I also believe there is still jewelry that belonged to Queen Astrid and then Princess Lilian which is unaccounted for. And, in fact, nobody knows exactly the current status of Queen Paola's personal jewels, not to mention some of Queen Fabiola's pieces.