Brownstone/Fieldstone Foundation Wall Renovation

What a great forum! I am very glad I found you guys! We live in a house with a foundation from 1900 – the rest of the house was renovated in 2007 but the foundation was kept as is. We are planning on installing a vapor barrier and french drain from DryZone BasementSystems. However, before I cover the walls with the vapor barrier, I want to make sure the walls are in good condition to be covered up. The foundation is ~8ft high, with the bottom half made of fieldstones and what looks like a lime-based mortar, and the top half is made of brownstones with a mortar that is much less crumbly. The brownstones are mostly above ground. When the renovation happened in 2005, the contractors covered the brownstones with a very sandy cement (inside and outside), which is now starting to blister and crumble off the wall (see Image 1). When you tap on what’s left, it sounds hollow and I get the sense it will be coming off soon as well. The fieldstones look like they are all still in good shape, but it’s covered in efflorescence in many areas (see Image 2) – which I believe is normal and the main reason for a vapor barrier in the first place. There are also some spots with the same sandy cement from 2005 (can also be seen in Image 2). Based on my research so far, it seems like covering these walls up as is would be a mistake. Instead, one should chip off all the bad cement, re-point with a high quality mortar, and then install the vapor barrier. Same goes for the outside. This, however, seems like a costly and time-consuming proposition for a house with a 700ft^2 footprint. Is there any way around this?