I believe there is an issue with oversupply of low tier filaments and undersupply of high tier filaments.
While a run may return no filament, often returns 2-4.
Since there are more filaments being generated than consumed, I suggest a “filament sink” (money sink for filaments to avoid oversupply) similar to what the game “Path of Exile” does with the maps.
Assuming a multiplier of 3:1 ratio. Could be a 5:1 or a 10:1 whatever CCP things is best.
One could transform 3 filaments (reprocess? combine? fuse?) of the same type and tier and get a filament of the tier above, either same tier or different tier, whatever CCP thinks is best.
This will lead to the filaments costing naturally x times more than the same filament of the previous tier, and solve the oversupply of lower tier filaments and the undersupply of high tier filaments.
Lowering the drop rate of the filaments will solve the oversupply of low tier filaments, but not the undersupply of high tier filaments.