Hyperbole, any mirror organisms we cook up will be simple and inefficient since they won’t be able to make easy use of the abundance of material that is the wrong chirality for their biochemistry. If they escaped they’d starve to death because all the normal life would be scavenging all the food sources much more effectively.
Converting from one lossless to another is still transcoding as you are changing the encoding format of the data. The conversion being lossy or not is related to the choice of formats, not the process itself.