We're definitely getting that impression as well. "all that can be done is being done" is the latest from on high, which is obvious rubbish.
What could (can) be done in reality is
A. maintain the airplanes to the same schedule as BA used when they had them and replace the seals at half engine life or less,
B. Replace the engines as soon as they show any signs of trouble, or at least replace the seals.
C. Replace the airplanes altogether
D. Replace the 535C engines with E4 engines
Any of these would solve the problem, but they all cost, to some degree or another. Any of these options will cost DHL more than we're worth to them and they're simply relying on the fact that it is difficult to link any health problems to the fumes situation. In other words, they're gambling the money they are saving by not doing the necessary now will not have to be laid out later in care for the pilots they have injured.
Nice fellas.