Renderd: ERROR: relation "country" does not exist at character 41

[morxw96]

I've tried to build a tileserver using this imposm-/tilery approach but unfortunately it doesn't work in my case. I followed all Steps described in the readme but ended up getting the same error again and again:
postgresql-script[]: ERROR: relation "country" does not exist at character 41
postgresql-script[]: STATEMENT: SELECT ST_SRID("geometry") AS srid FROM country WHERE "geometry" IS NOT NULL LIMIT 1;
renderd[]: ERROR **: An error occurred while loading the map layer 'pianoen': Postgis Plugin: ERROR: relation "country" does not exist
renderd[]: LINE 1: SELECT ST_SRID("geometry") AS srid FROM country WHERE "geome...
renderd[]: ^
renderd[]: in executeQuery Full sql was: 'SELECT ST_SRID("geometry") AS srid FROM country WHERE "geometry" IS NOT NULL LIMIT 1;'
renderd[]: encountered during parsing of layer 'country' in Layer at line 3613 of '/var/raid0/tileserver/pianoforte/dist/pianoen.xml'
renderd[]: ERROR **: Received request for map layer 'pianoen' which failed to load

It seem's like the Country table is missing but the imposm process ran through without any errors:
8:54:45 [step] Finished: Rotating tables in 10.080339053s
8:54:45 [step] Finished: Imposm in 8h54m45.234154699s

Not sure if that's correct, but the Database seems kinda small for me (Using osm2pgsql with a working mapnik tilery server it was about 1.2TB in size) where my current Tilery DB is "only" 367GB in size.
As i can see no Country table so far here:
Liste der Relationen
Schema | Name | Typ | Eigentümer | Persistenz | Zugriffsmethode | Größe | Beschreibung
-------+-----------------------+---------+------------+------------+-----------------+---------+--------------
public | city | Tabelle | root | permanent | heap | 48 kB |
public | itl_boundary | Tabelle | root | permanent | heap | 59 MB |
public | osm_admin | Tabelle | root | permanent | heap | 5892 MB |
public | osm_aois | Tabelle | root | permanent | heap | 460 MB |
public | osm_buildings | Tabelle | root | permanent | heap | 112 GB |
public | osm_housenumbers | Tabelle | root | permanent | heap | 5707 MB |
public | osm_housenumbers_area | Tabelle | root | permanent | heap | 15 GB |
public | osm_landusages | Tabelle | root | permanent | heap | 46 GB |
public | osm_landusages_gen | Tabelle | root | permanent | heap | 4381 MB |
public | osm_natural | Tabelle | root | permanent | heap | 93 MB |
public | osm_places | Tabelle | root | permanent | heap | 536 MB |
public | osm_pois | Tabelle | root | permanent | heap | 238 MB |
public | osm_railway | Tabelle | root | permanent | heap | 850 MB |
public | osm_railway_gen | Tabelle | root | permanent | heap | 397 MB |
public | osm_roads | Tabelle | root | permanent | heap | 66 GB |
public | osm_roads_gen | Tabelle | root | permanent | heap | 3228 MB |
public | osm_transport_points | Tabelle | root | permanent | heap | 498 MB |
public | osm_waterareas | Tabelle | root | permanent | heap | 11 GB |
public | osm_waterareas_gen | Tabelle | root | permanent | heap | 1308 MB |
public | osm_waterways | Tabelle | root | permanent | heap | 14 GB |
public | osm_waterways_gen | Tabelle | root | permanent | heap | 788 MB |
public | spatial_ref_sys | Tabelle | root | permanent | heap | 6936 kB |

I guess i'm missing something, at the point, where i added the city.sql and the boundary.sql, since a country table doesn't seem to be part of th imposm mapping.json file.