It's the last save before I became aware of the problem:
Under cache, there's only AREA050A.bif and AREA0500.bif. The others are empty.
Some news: Waukeen's place is also making the game crash, just after I accepted Aster's offer.
For a non-exhaustive check of the remaining saves, Waukeen's is now affected systematically after chapter 3 aside from a brief moment when a cinematic is playing (thieves guild meeting in this case); with one random save and one after getting momentarly 15k gold(then removed via Shadow Keeper) but not with another random one in chapter 2; and accessible without trouble when getting out of Irenicus donjon. 2nd floor of the flagons remains affected in all cases.
But that becomes better; Even when both non-patch mods are desactivated, Waukeen's can't be reached in last save before bug. Also, I formally recall going on Waukeen's area before creating Aster in the 1st floor and accepting the quest.
Conclusion; I do not longer assume that Alternatives is implicated, as I can't discern the specifics of what provokes the crash. I'm a little short in time for further saves check, but I will keep an eye here as well as report any solution that I may find.
Edited by Lumin, 28 January 2016 - 08:17 AM.