A few months later I got a second test. Both VLaMax (+0.26 mmol/l/s) and VO2Max (+6.9 ml/min/kg) came out significantly higher. That high, it triggered them to recheck the first test I presented in the OP. Telling me that the data of the old measurement had led to a very rare behaviour of their algorithm, they sent me a corrected version of it (now the jump to the recent one is not not so high anymore). Since then, I played around with these models myself, however, my own Mader/Heck fits both old and new measurement perfectly using the more plausible values of VLaMax and VO2Max and is completely off with the ones of the OP 
Regarding the training directions, I think I took the right way (until now). @empiricalcycling posts made me think about them. I would decribe INSCYD like a compass, it tells you that your goal (with respect to lactate dynamics) is left or right of you. But if you’re balanced the way you strive for, these values do not help you to move forward. We need a GPS 
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