Mm, but the weapon fires by launching wire through the coin, a jam would mean there's either an error with the wire spool (unlikely because of the mechanism's extreme simplicity), in which case the dejamming bolt would need to spool a new length and leave the coin in place, discarding any wire that might already be 'in the chamber'; or there is a malfunction in the firing mechanism, a coil gun, which cannot be remedied by simply exchanging a new coin and piece of wire. Additionally, since the wire-spool mechanism already has to be automated since there is no mechanism to recock the weapon and set up the next shot through the firing process, an automatic and compact dejammer is probably already in place much like how a chain gun avoids jamming due to a misfire by having an automated ammunition feed that pulls the shells through the breach rather than rely on blowback or recoil cocking.
In the case of the HPAR, a misfire either means the spool is defective and should be replaced, the coin is defective and should be replaced, the accelerator that fires the wire is defective or miscalibrated and the weapon is useless or ruined, or a combination of two or all three of the previous issues have most probably ruined the weapon. In the first two cases a "chain gun" feature should discard both the wire and coin and attempt to fire the next round with no intervention by the operator; In the last two cases the weapon must be repaired or, more probably, replaced entirely, both if which make it immediately useless to the soldier holding the weapon.
The HPAR is really a high-end piece of military equipment, any malfunction in the field is likely due to a complex failure within the electronics that cannot be fixed by the operator unless they are a tech sentry with the proper tools. An autodiagnostic is likely in place to assay what has malfunctioned, but pulling the weapon apart in the field to fix an electronic issue would probably only make the situation worse by fouling up any working electronics through elemental exposure.
I always saw the weapon as a robust SFP coilgun, not an M16 in space, which, as cool as the visual upgrade and extra options are, is what it seems you're trying to make the HPAR into and I would strongly suggest against that. The weapon is a rapid fire heavy anti-armor rifle, not an infantryman's AR; it may be an analogue, but it really shouldn't be identical.
On my issue with the silencer, reducing the round's velocity would reduce its kinetic force, the primary method by which this weapon does its job, which is to defeat enemy heavy armor. Keeping in mind that this is an assault weapon in every sense of the word, it defeats the foe through a mass of warheads and a considerable ammunition supply. Just see how long on fully automatic (420rpm) it takes to empty the 700-round magazine by discharging the weapon as fast as possible; over a minute and a half. The only other type of weapon to have a single magazine of that size are gattling-style cannon or large missile pods, neither of which are at all silent or stealthy weapons when fired. If the operator is on a mission where silence and likely precision as well is needed, this is not the kind of weapon to carry, nor would a silencer help.
IIRC, a silencer absorbs the propellant gases from a discharged bullet, reducing flash and muffling the noise, it does not reduce the supersonic zip of the round which you must cold-load the cartridge with reduced propellant to account for. Simply making the weapon "less supersonic" does nothing to help the noise issue, in fact it would give the enemy more time to react. On the issue of absorbing the flash of discharge, the silencer would likely be ruined quickly from the semi-molten metals clogging or deforming the silencer. I could possibly see using a baffle to direct the noise of firing towards the front of the weapon and reduce sideways transmission of noise, but the silencer just seems silly to me.
