1. There appears to be adequate room for a rectangular 90 degree transition, but it would encroach slightly into what appears to be a setback from an adjoining building. No information is given regarding that separation, but perhaps it can be 'violated' to solve the ramp design deficiency.
2. It appears the original post and follow-up provide an answer. A continuous curved ramp 'through' the transition area could work, and looks viable (with perhaps a very small encroachment into the same setback mentioned above.
3. What appears to be a narrow planting strip next to the 'lowest' parking stall could be eliminated, and the ramp condition improved as a result.
4. Can the 'lowest' parking stall (apparently a compact stall) be shifted slightly to the left, to align with the stall at the very top of the drawing, providing more flexibility at the 'corner' area?
5. I would caution the designer that the ramp as designed is problematic if taking into account the difficulties (or even impossibility) of building the ramp with the kind of Swiss watch tolerance called for - essentially zero tolerance is anticipated by the design. This is a scenario that predictably will result in technical failure to comply with code once constructed... and will fall further out of conformance with time, as site soils compact and shift under localized ramp portions. It is not advisable to specify ramps that are at the absolute maximum allowed slope. At a minimum, the design parameters should be adjusted to something less than maximum to account for industry-allowable and specification-allowable construction tolerances for finished site concrete work.
6. If it is not possible to obtain agreement to an encroachment into the the setback mentioned in 1 and 2, above, and if the present overall site configuration/layout does not allow for slightly longer aggregate ramp runs, then the designer should go back to square one and perform some magic in the way of adjusting the site plan and/or grading so that that there is room for the ramp and there is a lesser total elevation gain from end to end of the ramp system. There is no 'forgiveness' for violations under ADA (a federal civil rights law, not state building code), especially for new construction. Even following 'guidance' from DOJ is not a safe harbor. Despite what any code official or CASP might say is OK, if the ramps are not fully compliant when constructed, and not maintained in a fully compliant condition post-construction due to foreseeable soils settlement, an aggrieved party can bring suit against the property Owner (who, in turn, can look to the designers in a negligence suit). The costs of defending a suit (even one that is without merit), and the potential monetary and re-construction penalties are risks that can be guarded against by both designer and owner. Failure to avoid known risk is not a preferred route.