Putting a variable into a variable?

[ShreckAndDonkey]

I've got a bot that, on command, creates a set of variables for a user that are named using their ID and _bp/_ap/_detentions/_isolations. These are formatted as ${tempVars("emtcreateid")}_ap/_bp/_detentions/_isolations and this works fine. I'm working on another command to view the value of the created variables, and so far, it:
- stores the member ID, display name and avatar URL of the mentioned param user
- stores the display name and avatar URL of the command user
- sends an embed including the above as well as the values of the variables
^^^ this is where the problem starts. Because my variables are named using IDs, when trying to view them I need to use the stored ID of the mentioned param user to grab the variable, but that requires a variable in a variable, as follows:

${tempVars("${tempVars("viewemtprofileid")}_ap")}

My attempts have been unsuccessful and I feel like I'm just missing something obvious or whether it's just impossible, but here's the resulting log output:

  Starting bot at version: "2.1.5"
 ? SyntaxError: missing ) after argument list
 ?     at Object.Actions.eval (C:\Users\Test\Desktop\Test\bot.js:1229:17)
 ?     at Object.Actions.evalMessage (C:\Users\Test\Desktop\Test\bot.js:1239:15)
 ?     at Object.action [as Send Message] (C:\Users\Test\Desktop\Test\actions\send_message.js:633:66)
 ?     at processTicksAndRejections (node:internal/process/task_queues:96:5)
 ? 
 ? C:/Users/Test/Desktop/Test/node_modules/discord.js/src/util/Util.js:427
 ?     if (typeof data !== 'string') throw new error(errorMessage);
 ?                                         ^
 ? 
 ? RangeError [EMBED_FIELD_VALUE]: MessageEmbed field values must be non-empty strings.
 ?     at Function.verifyString (C:/Users/Test/Desktop/Test/node_modules/discord.js/src/util/Util.js:427:41)
 ?     at Function.normalizeField (C:/Users/Test/Desktop/Test/node_modules/discord.js/src/structures/MessageEmbed.js:544:19)
 ?     at C:/Users/Test/Desktop/Test/node_modules/discord.js/src/structures/MessageEmbed.js:565:14
 ?     at Array.map (<anonymous>)
 ?     at Function.normalizeFields (C:/Users/Test/Desktop/Test/node_modules/discord.js/src/structures/MessageEmbed.js:564:8)
 ?     at MessageEmbed.addFields (C:/Users/Test/Desktop/Test/node_modules/discord.js/src/structures/MessageEmbed.js:328:42)
 ?     at MessageEmbed.addField (C:/Users/Test/Desktop/Test/node_modules/discord.js/src/structures/MessageEmbed.js:319:17)
 ?     at Object.action [as Send Message] (C:\Users\Test\Desktop\Test\actions\send_message.js:633:19)
 ?     at processTicksAndRejections (node:internal/process/task_queues:96:5) {
 ?   [Symbol(code)]: 'EMBED_FIELD_VALUE'
 ? }
 ? 
 ? Node.js v17.4.0
 ? 

Thanks in advance for your help!