What Ian explains is exactly as in the document I have send.
Do not worry about the loss of 8% That is actually very good.
It can be more upon till 15 or 20 % with a leak down test.
There are more reasons for loss in pressure with a leak down test.
When you did a proper leak down test as explained then there is no problem in the cylinder so do not open the engine.
The oil use of nearly 1 liter? ( US Gallons or Imp ? ) in 200 miles is frightening.
Nearly impossible that valves are a problem you should see that at the exhaust. As a lot of white smoke.
No smoke - or only when cold - in that case probably the valves are good.
I lost oil too and found that when parked.
I had a problem with the hose clamps at the oil tank and changed them all to an other type and used 2 of them at each point IN and OUT.
The most important one is the big one [ IN ] at the top because there is 3- 4 Bar pressure on it.
I used special Boltza Hose clamps and they were the only ones who finally solved my problem.
They are ugly but do their job.
I looked for you on amazon.com but could not find them, but - To see what I mean - have a look at :
https://www.amazon.fr/Boltza-colliers-serrage-plaqu%C3%A9-passante/dp/B0B8DY8HP2?pd_rd_w=XiJpr&content-id=amzn1.sym.9d33c282-f4cb-47c9-bba8-60e74e550e84&pf_rd_p=9d33c282-f4cb-47c9-bba8-60e74e550e84&pf_rd_r=HRDZVEHCTM743B2Y1G32&pd_rd_wg=Cc4gc&pd_rd_r=09ec1bfb-2e29-4f64-be83-b624807b481e&pd_rd_i=B0B8DY8HP2&psc=1&ref_=pd_bap_d_grid_rp_0_1_ec_pd_rhf_ee_s_rp_c_d_sccl_1_4_i
