The verb is 在る / 有る (aru) Link
but the second issue appears to affect all verbs.
for the imperative plain form of ある, the site has 有い あい ai
I'm fairly sure it should be あれ
To get あい, for an imperative form, you would have to follow the special honorific verb conjugation rules. Examples of that: なさる conjugates to なさい, ござる conjugates to ござい, etc.
for the imperative polite form, the site has 有りませ ありませ arimase
As far as I can tell, a ～ませ form doesn't exist. It looks most like the polite negative form ～ません and that's what the translator thinks it is. This looks like a script issue because all the verbs seem to have this for their imperative polite form. The sites I checked (and my notes) have it as ありなさい for this verb. That's standard 五段 conjugation (～いなさい). While, for comparison, 一段 is ～なさい.
Sorry about this, another bug to fix 🙁
Anyway, I've been working on conjugation all day and my head hurts. On the bright side, though, my conjugation spreadsheet can now make a total of 75 potential forms per verb (and that's not counting 敬語 forms). Now to memorize all of them lmao 🤣