No, it's not a problem if you use K610_R1KG001_FS_T_MOB_INT_A_RED52, but you'll have a branded phone. If you want to debrand, too, you must use K610_R1KG001_FS_EUROPE_2_RED52(English - French - German - Sesotho - Zulu - Turkish). If you want dutch language too, you must use an older version k610_R1JG001_FS_EUROPE_3_RED52(English - Danish - Dutch - French - German). You can't have Polish, German and Dutch with "generic" firmware.
Why don't you convert your K610 to W660 with this newer firmware:
W660_R8BB001_MAIN_GENERIC_FY_RED52
W660_R8BB001_FS_EUROPE_3_RED52 and custom file
HB1-06_Gen_CDA102568_12_R8A_GENERIC_EUROPE_3 ?
If you want to, search around for "Converting K610/K618/V630, Z610 and K530 to W660. Full Guide!"