i've lost (melted) nurii, hudoroi, parva, cordata thailand, lucens, pygmaea in an attempt to convert to emersed growth.
this was me literally taking the plant and plucking them into soil mesh pots. i've found that some crypts are just more resilient and hardy. most common crypts like the wendtii, ponterdifolia seem to be very hardy and have no issue converting.
i do believe the pH of the soil has something to do with the success of the plant, more importantly if the soil itself is "converted" to a submeged state. i don't have any clincal proof to back this up, just my subjective observations, but... i've found most of my plants only started thriving when i planted them in converted soil. soil that has been submerged for at least three
months. thats why i keep barren pots with soil (some stratum and some topsoil only) submerged in my emersed tank. Now i can pluck almost anything in there and it will thrive and grow. This includes lanky stems like mini limno, sunset hygro and even rotalas.
if you do not want to take chances and you just want to pluck and plant...the most stable soil i've had success with is fluval stratum or similar aquasoil type. it lends itself to being submerged from the start. throw an osmocote capsule in there for good measure. good luck!