Sorry I missed this very important data you provided. I punched in the numbers in my calculator and can confirm that the relative differences between your ceiling bounce measurements and TA tube measurements are practically the same, which rules out your original concern that TA tube readings are only reasonable for low output lights and more inaccurate for high output lights. Now this makes everything easy. It could likely be there’s a problem with the calibration on your specific unit, which is easily fixable, which TA did for us a while ago. All you need to do is buy the Maukka calibration lights. If TA tube indeed measures lower, then let TA know and he will provide a solution to modify apply a correction factor. If it reads the same, then some of your high output lights are indeed that low. There were many postings of high output lights measured by TA tubes before on this thread and elsewhere and their numbers were very reasonable (e.g., my M43 measures 6,950 lumens whereas you measured 4,550 lumens), so what you reported is definitely a one-off experience thus far.
If you are concerned that using lower output lights for calibration might not be suitable for high output lights, I provided links in my previous post above to Maukka’s explanations that should alleviate your concern.