The translation was faithfull to the comment, but the comment was wrong :
in order to translate a condact, we need clocks (when) !

node condact_toto(i0:bool; i1:int; i2:int) returns (o0:int) = Lustre::condact<<toto, 0>>;

is now translated into:

condact_toto(i0:bool; i1:int; i2:int) returns (o0:int)
let
  o0 = if i0 then current(toto(i1 when i0, i2 when i0) ) else (0 fby o0);
tel