I had an R5 (LeCar) and took it apart. It had a lot of smog equipment that was improvised when the car was imported into the US that it was never intended to have in France or in other countries where Renaults were sold. The imported R5s tended to overheat and blow head gaskets. But Renaults have often performed very, very well in Europe and throughout the world. The Renault Dauphine from the 1960s was not a good design and tended to roll in sharp turns and the Floride/Caravelle was underpowered for a sporty type of car. The world's first hatchback, the R16 was a rugged performer but not very exciting. The Renault R4L was a great little car, very rugged, that was sold throughout the world and especially in Latin America. The more recent Renault Twingo was a great little car. The Renault Alpine A110 in the 1960's was perhaps the greatest sports car of its generation. But you are right about the LeCar and the Alliance. They were not among Renault's best designs. But several Volvos used Renault 1.4 liter and 1.7 engines. The Lotus Europa also used a Renault engine (more reliable than the alternate Cosworth).
As far as French automotive engineering in general, I consider the Citroen DS21 to be one of the greatest engineering masterpieces of all time in any street production car. I own one from 1969 and it's still on the road, running like a clock. As you can probably tell, I'm an old car fan, but I'd like to have a new Citroen C4, however. It's the only new car I'd care to own: