What is the current status of Paraphrenia?
Paraphrenia is a late-onset mental disorder similar to schizophrenia in that it features the positive symptoms of the disease, such as delusions and/or hallucinations, but lacks the negative symptoms, such as the deterioration of intellect or personality. It seems to be an outdated term (source: Psychology Central).


  Can anyone find a well-focused and detailed experimental review or trial?  


I have found a few, albeit all somewhat dated: Ravindran et al. (1999); Lubman &amp; Castle (2002) and Sato &amp; Idha, (2002). I can recommend to see whether these articles are cited in papers published on a later date if you prefer more recent literature.  


  Do psychology / psychiatry associations claim it?  


Difficult question. The International Late-Onset Schizophrenia Group recognizes the disorder’s late-onset version as “very late-onset schizophrenia-like psychosis Howard et al. (2000). The CCI in Australia describes it. Smaller, more isolated institutions seem to recognize it, for instance, the Cardif &amp; Vale Action for Mental Health at least acknowledges its existence. As you said, it appeared not in the DSM-IV and V manuals. Instead, more recently paraphrenia has been classified as 


  very late-onset schizophrenia-like psychosis


Patients who present these particular symptoms are generally diagnosed with a variety of other illnesses, including atypical psychosis, schizoaffective disorder, delusional disorder or persistent persecutory state (source: Psychology Central). I am sure when you search under this term you will end up with substantial amounts of resources, including for example the DSM-V manual, where it is included, albeit quite vaguely defined according to Sachdev et al. (2015).


  Manuals that address it in diagnosis or didactically?


Under the more popular name late-onset psychosis, you can find its diagnostic characteristics in the DSM-V manual as stated above, in The Psychosis Manual from Smith et al., in this Master's thesis, among hosts of other sources.  

References
- Howard et al., Am J Psychiatry (2000); 157(2): 172-8
- Lubman &amp; Castle, Current Psychiatry (2002); 1(12): 35-44
- MacDougall, Master's thesis (2011), McMaster University
- Ravindran et al., Can J Psychiatry (1999); 44(2):133-7
- Sachdev et al., Harv Rev Psychiatry (2015); 23(5): 320–8
- Sato &amp; Idha, Psychogeriatrics (2002); 2(1): 20–5