What were the achievements? and am befuddled by this qoute
French historian Jacques Godechot points out “The French were strongly attached to the essential achievements of the Revolution, and Louis XVIII had come back ‘in the baggage train of the foreigners’ with the last surviving émigrés who had ‘learnt nothing and forgotten nothing’ and whose influence seemed to threaten most of the Revolution’s achievements"
What is meant by "learnt nothing and forgotten nothing" (often misattributed to Talleyrand) and the larger point of Godechot is that Louis XVIII and his more extreme supporters were operating under the mistaken belief that they could turn back time and restore the France to something that approached pre-revolutionary society. The Bourbon's domestic policies which seemingly undercut all the gains of the Revolution contributed to a sense that the Louis XVIII was out of touch with France and did not grasp the changes that had occurred in the country since his exile. Although the Bourbons had pledged not to engage in political retributions, Louis XVIII's government actively purged the state of those who had been active during the Revolution and started to pressure for the return of the biens nationaux lands that had been acquired during the Revolution.
These policies alienated two key constituencies within France between 1814-15. Firstly, many within the French army felt threatened by the fiscal retrenchment and cuts to its establishment. Bourbon politics also undercut the deep bonds of loyalty and esprit de corps within the military itself as it eliminated the symbols of the Grand Armee like the tricolor. The second group were surviving revolutionaries and others of a liberal political bent that wanted a constitutional monarchy. When Napoleon returned to France during the Hundred Days, both these groups flocked to him; although French liberals were more qualified and lukewarm in their support for Napoleon than the military.
One of the chief accomplishments of Louis XVIII was the Charter of 1814, which gave France a semblance of a party system. While not a democracy in the formal meaning of the word, the Bourbon king had strong executive powers, the direction of French domestic and foreign policy became highly acrimonious between Waterloo and the July Revolution of 1830, with many liberals like Lafayette arguing for a constitutional monarchy. Although the resulting political acrimony makes this a dubious accomplishment of the Bourbons, the commitment to the Charter was atypical compared many other Reactionary states of the post-Congress of Vienna period, which grafted on Napoleonic/Revolutionary innovations in state structures like conscription to autocratic systems.