I do not know where you get your duff information from with regards to routine fuel filter maintenance.
I can not state for the B747-8, but l can with 100% accuracy for the B787 tell you that both the LP and HP fuel filters are replaced at 2000 FH & 30000 FH respectively.
Just in case you think l am writing bull
, the MRBR/MPD task numbers for RR powered B787s are as follows, 73-205-01 & 73-205-02 for LP filter and 73-210-01 & 73-210-02 for HP filter.
Now for the second correction, LOT have 5 a/c in service and have had a total of 11 engines fitted. All engines currently fitted were checked last week, with only the engine on repair at RR requiring a check if not already done so.
The only mystery is why only one engine at fault on SP-LRC, when both FOHE were changed after the test flights, due to contamination.
The FOHE are supplied without the LP filter being fitted and the norm is the AMM procedure (which Boeing publishes) has a step to install the filter as part of the FHOE replacement.
However Boeing does not use the AMM and relies on job cards for all its requirements, first step for Boeing QA to look at.
We know that 5 engines had the FOHE replaced at some point after engine delivery from RR, 3 found to have LP filters missing.
As l have pointed out none of the LOT a/c have reached 2000 FH and have not had any of the filters replaced.
SP-LRB has today returned to service after the engine component changes and all engine inspections were carried out, plus the original defect was finally fixed.
My belief is that a Boeing working party has been involved in returning the a/c to service.
It also looks like your 21.3 report you talk of, is pretty much fiction.