Fixing ngerman bibliography strings

I have added/replaced 5 bibliography strings in ngerman-apa.lbx, following the latest manual from the DGP 4th ed. from 2016.

[...]
  on               = {{auf}{auf}}, % <== CHANGED (not according to the DGP manual but German grammar)
  retrieved        = {{verfügbar}{verfügbar}}, % <== CHANGED
  inpress          = {{im Druck}{im Druck}}, % <== NEW, probably not needed because the identical string can also be found in biblatex's german.lbx
  nodate           = {{nicht\space datiert}{{}n\adddot\addabthinspace d\adddot}}, % <== NEW
  abstract         = {{Abstract}{Abstract}}, % <== NEW, used according to the first example on p. 124. On p. 129 Zusammenfassung and Auszug is alternatively suggested, but let's keep it simple.
[...]

These work fine when placing the ngerman-apa.lbx in my texmf directory, see the following MWE:

\documentclass[paper=a4]{article}
\usepackage[ngerman]{babel}
\usepackage{csquotes}

\usepackage[style=apa]{biblatex}

\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
% (APA 7.01 Example 6)
@ARTICLE{7.01:6,
    AUTHOR         = {R. Briscoe},
    PUBSTATE       = {inpress},
    TITLE          = {Egocentric Spatial Representation in Action and Perception},
    JOURNALTITLE   = {Philosophy and Phenomenological Research},
    URL            = {http://cogprints.org/5780/1/ECSRAP.F07.pdf},
}

% Note use of ABSTRACTURL field value to specify that the URL is for the abstract
% and so the entry gets "Abstract retrieved from" instead of just "retrieved from"
@ARTICLE{7.01:16b,
    AUTHOR         = {S. R. Lassen and M. M. Steele and W. Sailor},
    TITLE          = {The Relationship of School-wide Positive Behavour Support to Academic Achievement in an Urban Middle School},
    JOURNALTITLE   = {Psychology in the Schools},
    VOLUME         = {43},
    PAGES          = {701--712},
    DATE           = {2006},
    ABSTRACTURL    = {http://www.interscience.wiley.com},
}

@ARTICLE{7.01:17,
    AUTHOR         = {L. R. Hare and K. O'Neill},
    TITLE          = {Effectiveness and Efficiency in Small Academic Peer Groups},
    JOURNALTITLE   = {Small Group Research},
    VOLUME         = {31},
    PAGES          = {24--53},
    DATE           = {2000},
    ABSTRACTLOC    = {{S}ociological {A}bstracts database. (Accession No. 200010185)},
}

% (APA 7.02 Example 20)
@BOOK{7.02:20,
    AUTHOR         = {E. O'Keefe},
    TITLE          = {Egoism \& the Crisis in {W}estern Values},
    URL            = {http://www.onlineoriginals.com/showitem.asp?itemID=135},
}

% (APA 7.03 Example 33)
% Use URLDESCRIPTION to introduce website address; defaults to just "Retreived from"
% if not present
@REPORT{7.03:33,
    AUTHOR         = {S. S. A. Kessy and F. M. Urio},
    TITLE          = {The Contribution of Microfinance Institutions to Poverty Reduction in {T}anzania},
    TYPE           = {Research Report},
    NUMBER         = {06.3},
    DATE           = {2006},
    URLDESCRIPTION = {Research on Poverty Alleviation website},
    URL            = {http://www.repoa.or.tz/documents_storage/Publications/Reports/06.3_Kessey_and_Urio.pdf},
}

% (APA 7.07 Example 52)
% Note use of SORTKEY to make sorting ignore the lower case AUTHOR
@MUSIC{7.07:52,
    SORTKEY        = {Lang, K. D.},
    ENTRYSUBTYPE   = {{CD}},
    AUTHOR         = {{lang}, {k.}{d.}},
    TITLE          = {Shadow and the Frame},
    MAINTITLE      = {Watershed},
    MAINTITLEADDON = {{CD}},
    LOCATION       = {New York, NY},
    PUBLISHER      = {Nonesuch Records},
    DATE           = {2008},
}
\end{filecontents}
\addbibresource{\jobname.bib}

\begin{document}
    \cite{7.01:6} for im Druck and Verfügbar unter

    \cite{7.01:16b} for Abstract

    \cite{7.01:17} for Verfügbar über ... Datenbank

    \cite{7.02:20} for n. d.

    \cite{7.03:33} for Verfügbar auf ... Website

    \cite{7.07:52} for Auf
    \printbibliography
\end{document}

There are 4 issues remaining:

7.01:6: It should be

(im Druck).

(preposition in lowercase), but it gets printed as

(Im Druck).

7.01:17: Now it's

Verfügbar unter ..., e.g., Sociological-Abstracts-Datenbank:

However, the German term for database needs a different preposition:

Verfügbar über ...

plk / biblatex-apa

Fixing ngerman bibliography strings #59