...o software FW3 era recomendável, mas não necessário. ...
..."the software FW3 was recommended, not mandatory..."
Portuguese is not my native language but shouldn't your translation be thus :
"...the FW3 software was advisable, but not necessary. (wasn't considered necessary) ?
the word *recomendāvel* has the suffix *avel* which is the equivalent of *able* in English, therefore *recomendāvel* becomes *recommendable* or *advisable*
*necessārio* has never meant *mandatory*.
Translating to suit your arguments, aren't you ?