"unter anderem" and "vor allem" in German

[verenablaschke]

While inspecting the errors flagged by the new det-clf-leaf rule in the German HDT treebank, we noticed (among other things) the following error type (cf. #1059 (comment)): the expressions "unter_ADP <-case- anderem_DET" ("among other things", lit. "under other") and "vor_ADP <-case- allem_DET" ("especially", lit. "before all") are currently annotated as det when modifying a noun phrase.
For instance: "Dieser Vorschlag ist bislang jedoch unter anderem am Widerstand Großbritanniens gescheitert" ("However, this suggestion has failed among other things because of opposition from Great Britain") current is annotated as "unter anderem" modifying "Widerstand" ("opposition") with the deprel det.

Sentences where "unter anderem" modifies a verb/sentence are currently largely annotated correctly: modifying the verb/root as obl. (E.g., "In einem begleitenden Wettbewerb sollen Schüler unter anderem Online-Magazine entwickeln , Multimedia-Kunstwerke gestalten oder das Telefon der Zukunft planen ." / "In an accompanying competition, students are asked to, among other things, develop online magazines, design multimedia artworks and plan the telephone of the future." with "unter anderem" modifying "[Online-Magazine] entwickeln" / "develop [online magazines]" as obl).

We are planning to change the deprel labels of "unter anderem"/"vor allem" modifying noun phrases to nmod in HDT. Please let us know if you don't agree with this decision.

Our plan is to only modify HDT for now, but similar issues (and det-clf-leaf errors) occur in all other German treebanks (possibly in treebanks for closely related languages as well, but we haven't checked).

cc: @LeonieWeissweiler @nboebel