Proposal 1
affix type meaning cognates example
-bel number → attribute the multiple of the referred number tvobel (double)
-er verb → noun a person, that does what is described in the referred verb en:-er, de:-er baker (baker(man))
-et number → attribute ordinal number en:-th, de:-t tvoet (second)
-het attribute → noun the abstract attribute described by the referred property de:-heit, nb:-het gladhet (happiness)
-ien noun → noun a member of the country or similar en:-ian Kanadien (Canadian)
-ig noun → attribute an attribute implied by the referred noun basig (basic)
-in noun → noun indicating the sexus “female” de:-in levenin (lioness)
-ir attribute → verb to make something have the referred ability de:-ier svartiren (to blacken)
-let noun → noun smaller version buklet (booklet)
-ling noun → noun offspring of the referred noun hundling (puppy)
-mal number → […] repetition tvomal (twice)
-ning verb → noun something that arises from the referred verb de:-ung, en:-ing, nb:-ing beslisning (decision)
-ort verb → noun a place to do what the verb describes grindort (mill)
-sam verb → attribute smartsam (painful)
-ska […] → attribute Svenska (Swedish)
-tel number → attribute the fraction of the referred number de:-tel tvotel (half)
Proposal 2
affix type meaning cognates example
-rid verb → noun the act described by the referred verb is:-ri, en:-red, de:-rei hatrid (hatred/hating)
-ung verb → noun something that arises from the referred verb de:-ung, en:-ing, nb:-ing givung (gift)
-ar verb → noun a person, that does what is described in the referred verb nn:-ar, sv:-ar, en:-er, de:-er sprekar (speaker)
-bar verb → attribute the possibility to do, what the referred verb describes de:-bar, nb:-bar denkbar (thinkable)
-lik noun → attribute having the abilities of the referred object en:-ly, de:-lich, nb:-lig bruderlik (brotherly)
-ig noun → attribute with the referred object en:-y, de:-ig bludig (bloody)
-isk noun → attibute belonging to the referred object en:-ish, de:-isch, nb:-isk dutisk (german)
-en attribute → verb to make something have the referred ability en:-en, de:-en harden (harden/make hard)
-hed attribute → noun the abstract attribute described by the referred property de:-heit, nb:-het frihed (freedom)
un- attribute → attribute negation of the referred attribute en:un-, de:un-, nb:u- unfri (unfree)

Comment: during a conversation in the FB group, -kin was mentioned as a possible diminutive suffix.

Footnote. Out of interest, even though -er is the standard English suffix for people-who-do, the following words in -ar exist: beggar, burglar, bursar, liar, pedlar, registrar, scholar, vicar.