I do not have any knowledge of Pali but i belief the statement ‘what is impermanent…is suffering’ is probably only introduced as a very condensed formula within a more bigger picture/teaching in which people allready know that anything that is impermanent is also conditioned, dependently arisen, subject to destruction, to vanishing, to fading away, to cessation and therefor cannot provide lasting happiness and cannot function as a refuge.
Clinging to such impermanent things is unskillful, suffering.
Nice feelings, for example, come with a certain happiness but when they vanish also with a certain unhappiness because they are gone and one wants them to be there again. So even when states are nice, even jhana, their nature of impermanance comes also with suffering as long as there is longing and irrealistic expactations of conditioned states.
Therefor the very condensed formula…what is impermanent is suffering, can be useful and truthful too, but one must see it in the context, like anything.
I think Lal’s explanation of anicca, dukkha and anatta will lead to the same mindset, but i belief that it will probably take less time when anicca is translated as ‘one cannot maintain anything like one wishes’.
My (small) objection to this translation is that this is very close, or almost the same, as what dukkha also means.
But, in the end, i feel, the expressed message is the same.
Siebe